This library allows ESP32 to send Email with/without attachment and receive Email with/without attachment download via SMTP and IMAP servers.
The library was test and work well with ESP32s based module.
Copyright (c) 2019 K. Suwatchai (Mobizt).
This following devices were tested and work well.
- Sparkfun ESP32 Thing
- NodeMCU-32
- WEMOS LOLIN32
- TTGO T8 V1.8
- M5Stack ESP32
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Support Email sending with or without attachment via IMAP server.
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Support SSL/TLS and STARTTLS protocols.
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Working with SD card allows large file attachment supported or SPIFFS for small file size attachment.
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Support Email reading via search and fetch modes (with or without attachment downloads).
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Support large attachment download via SD card or SPIFFS for small file size attachment.
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Message text and its header are able to download and save to SD card or SPIFFS.
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Support Email message fetch and search via IMAP command as in RFC 3501 (depending on IMAP server implementation).
For library version 1.2.0 and newer, STARTTLS was supported and can be enable automatically when port 587 for SMTP was used or can set manually thrugh smtpData.setSTARTTLS(true) and for IMAP through imapData.setSTARTTLS(true).
Click on Clone or download dropdown at the top of repository, select Download ZIP and save file on your computer.
From Arduino IDE, goto menu Sketch -> Include Library -> Add .ZIP Library... and choose ESP32-Mail-Client-master.zip that previously downloaded.
Go to menu Files -> Examples -> ESP32-Mail-Client-master and choose one from examples
Declaration and Initialization
The first thing to do to use this library.
//1. Include ESP32 Mail Client library (this library)
#include "ESP32_MailClient.h"
//2. For sending Email, declare Email Sending data object in global scope.
SMTPData smtpData;
//Or
//For receiving Email, declare Email receiving data object in global scope.
IMAPData imapData;
//3 Setup SMTP server login credential in setup()
smtpData.setLogin("smtp.gmail.com", 587, "[email protected]", "YOUR_EMAIL_PASSWORD");
//Or
//Setup IMAP server login credential in setup()
imapData.setLogin("imap.gmail.com", 993, "[email protected]", "YOUR_EMAIL_PASSWORD");
//4 For SMTP, set some custom message header (optional)
smtpData.addCustomMessageHeader("Date: Sat, 10 Aug 2019 21:39:56 -0700 (PDT)");
smtpData.addCustomMessageHeader("Message-ID: <[email protected]>");
//5 To debug for SMTP
smtpData.setDebug(true);
//Or IMAP
imapData.setDebug(true);
//6. Send Email
MailClient.sendMail(smtpData));
//Or Receive Email
MailClient.readdMail(imapData));
Send and Receive Email
Compose Email
This library allows you to set sender, recipient, importance (priority), CC, BCC and attachment data (binary or from SD card file).
To set sender, use smtpData.setSender e.g. smtpData.setSender("Jarvis", "SOME_EMAIL_ACCOUNT@SOME_EMAIL.com").
To set priority, use smtpData.setPriority e.g. smtpData.setPriority("High").
To set message subject, use smtpData.setSubject e.g. smtpData.setSubject("ESP32 Send Mail Test").
To set message text, use smtpData.setMessage e.g. smtpData.setMessage("This is plain text message", false);.
To set sender, use smtpData.addRecipient e.g. smtpData.addRecipient("SOME_RECIPIENT@SOME_MAIL.com").
To add attachment, use smtpData.addAttachData e.g. smtpData.addAttachData("test.png", "image/png", (uint8_t *)imageData, sizeof imageData);.
When completed all required message data, sending Email MailClient.sendMail(net, smtpData).
Get Email
To read or receive Email, mailbox folder should be assigned via imapData.setFolder e.g. imapData.setFolder("INBOX").
Then set search criteria to search specified mailbox folder via imapData.setSearchCriteria e.g. imapData.setSearchCriteria("UID SEARCH ALL").
Then set search limit to limut the memory and time usages imapData.setSearchLimit.
From search criteria, UID of message will be available to fetch or read.
Whit search, body message and attachment can be ignore to reduce the network data usage.
Begin receive Email MailClient.readMail(net, imapData).
From above settings, you will get the following header information
Messsage UID via imapData.getUID.
Messsage ID via imapData.getMessageID.
Accept Language via imapData.getAcceptLanguage.
Content Language via imapData.getContentLanguage.
Sender via imapData.getFrom.
Sender Charset via imapData.getFromCharset.
Recipient via imapData.getTo.
Recipient Charset via imapData.getToCharset.
CC via imapData.getCC.
CC Charset via imapData.getCCCharset.
Date via imapData.getDate.
Subject via imapData.getSubject.
Subject Charset via imapData.getSubjectCharset.
In addition, by setting search criteria, the following infomation are available.
Mailbox folder count via imapData.getFolderCount.
Mailbox folder name via imapData.getFolder.
Supported flags count via imapData.getFlagCount.
Supported flags name via imapData.getFlag.
Total message in folder via imapData.totalMessages.
Total message from search result via imapData.searchCount.
Available message from search result (limited by imapData.setSearchLimit) via imapData.availableMessages.
When fetch specific message via imapData.setFetchUID, availability of attachment file can be determined via
imapData.getAttachmentCount for that message which will be automatically download by setting imapData.setDownloadAttachment(true)
prior to MailClient.readMail.
See full examples for all features usages.
These are all functions available from the library and the descriptions.
Global functions
Sending Email via SMTP server.
param smtpData - SMTP Data object to hold data and instances.
return - Boolean type status indicates the success of operation.
bool sendMail(SMTPData &smtpData);Reading Email via IMAP server.
param imapData - IMAP Data object to hold data and instances.
return - Boolean type status indicates the success of operation.
bool readMail(IMAPData &imapData);Get the Email sending error details.
return - Error details string (String object).
String smtpErrorReason();Get the Email reading error details.
return - Error details string (String object).
String imapErrorReason();Init SD card with GPIO pins.
param sck -SPI Clock pin.
param miso - SPI MISO pin.
param m0si - SPI MOSI pin.
param ss - SPI Chip/Slave Select pin.
return Boolean type status indicates the success of operation.
bool sdBegin(uint8_t sck, uint8_t miso, uint8_t mosi, uint8_t ss);Init SD card with default GPIO pins.
return Boolean type status indicates the success of operation.
bool sdBegin(void);Set the IMAP server login credentials.
param host - IMAP server e.g. imap.gmail.com.
param port - IMAP port e.g. 993 for gmail.
param loginEmail - The Email address of account.
param loginPassword - The account password.
param rootCA - Root CA certificate base64 string
void setLogin(const String &host, uint16_t port, const String &loginEmail, const String &loginPassword);
void setLogin(const String &host, uint16_t port, const String &loginEmail, const String &loginPassword, const char *rootCA);
Set STARTTLS mode to enable STARTTLS protocol.
param starttls - bool flag that enables STARTTLS mode
void setSTARTTLS(bool starttls);Set debug print to serial.
param debug - bool flag to enable debug
void setDebug(bool debug);Set the mailbox folder to search or fetch.
param folderName - Known mailbox folder. Default value is INBOX
void setFolder(const String &folderName);Set the maximum message buffer size for text/html result from search or fetch the message.
param size - The message size in byte.
void setMessageBufferSize(size_t size);Set the maximum attachment file size to be downloaded.
param size - The attachement file size in byte.
void setAttachmentSizeLimit(size_t size);Set the search criteria used in selected mailbox search.
In case of message UID was set via setFetchUID function, search operation will not process,
you need to clear message UID by calling imapData.setFetchUID("") to clear.
param criteria - Search criteria String.
If folder is not set, the INBOX folder will be used
Example:
SINCE 10-Feb-2019 will search all messages that received since 10 Feb 2019
UID SEARCH ALL will seach all message which will return the message UID that can be use later for fetch one or more messages.
Search criteria can be consisted these keywords
ALL - All messages in the mailbox; the default initial key for ANDing.
ANSWERED - Messages with the \Answered flag set.
BCC - Messages that contain the specified string in the envelope structure's BCC field.
BEFORE - Messages whose internal date (disregarding time and timezone) is earlier than the specified date.
BODY - Messages that contain the specified string in the body of the message.
CC - Messages that contain the specified string in the envelope structure's CC field.
DELETED - Messages with the \Deleted flag set.
DRAFT - Messages with the \Draft flag set.
FLAGGED - Messages with the \Flagged flag set.
FROM - Messages that contain the specified string in the envelope structure's FROM field.
HEADER - Messages that have a header with the specified field-name (as defined in [RFC-2822])
and that contains the specified string in the text of the header (what comes after the colon).
If the string to search is zero-length, this matches all messages that have a header line with
the specified field-name regardless of the contents.
KEYWORD - Messages with the specified keyword flag set.
LARGER - Messages with an (RFC-2822) size larger than the specified number of octets.
NEW - Messages that have the \Recent flag set but not the \Seen flag.
This is functionally equivalent to *"(RECENT UNSEEN)"*.
NOT - Messages that do not match the specified search key.
OLD - Messages that do not have the \Recent flag set. This is functionally equivalent to
"NOT RECENT" (as opposed to "NOT NEW").
ON - Messages whose internal date (disregarding time and timezone) is within the specified date.
OR - Messages that match either search key.
RECENT - Messages that have the \Recent flag set.
SEEN - Messages that have the \Seen flag set.
SENTBEFORE - Messages whose (RFC-2822) Date: header (disregarding time and timezone) is earlier than the specified date.
SENTON - Messages whose (RFC-2822) Date: header (disregarding time and timezone) is within the specified date.
SENTSINCE - Messages whose (RFC-2822) Date: header (disregarding time and timezone) is within or later than the specified date.
SINCE - Messages whose internal date (disregarding time and timezone) is within or later than the specified date.
SMALLER - Messages with an (RFC-2822) size smaller than the specified number of octets.
SUBJECT - Messages that contain the specified string in the envelope structure's SUBJECT field.
TEXT - Messages that contain the specified string in the header or body of the message.
TO - Messages that contain the specified string in the envelope structure's TO field.
UID - Messages with unique identifiers corresponding to the specified unique identifier set.
Sequence set ranges are permitted.
UNANSWERED - Messages that do not have the \Answered flag set.
UNDELETED - Messages that do not have the \Deleted flag set.
UNDRAFT - Messages that do not have the \Draft flag set.
UNFLAGGED - Messages that do not have the \Flagged flag set.
UNKEYWORD - Messages that do not have the specified keyword flag set.
UNSEEN - Messages that do not have the \Seen flag set.
void setSearchCriteria(const String &criteria);Set to search the unseen message.
param unseenSearch - Boolean flag to enable unseen message search.
This function will be overridden (omitted) by setFetchUID as setSearchCriteria.
void setSearchUnseenMessage(bool unseenSearch);Set the download folder.
param path - Path in SD card.
All text/html message and attachemnts will be saved to message UID folder which created in defined path
e.g. "/{DEFINED_PATH}/{MESSAGE_UID}/{ATTACHMENT_FILE...}".
void setSaveFilePath(const String &path);Specify message UID to fetch or read.
param fetchUID - The message UID.
Specify the message UID to fetch (read) only specific message instead of search.
void setFetchUID(const String &fetchUID);Set storage type to save download attached file or messages.
param storageType - The storage type to save file, MailClientStorageType::SD or MailClientStorageType::SPIFFS
void setFileStorageType(uint8_t storageType);Enable/disable attachment download.
param download - Boolean flag to enable/disable attachment download.
void setDownloadAttachment(bool download);Enable/disable html message result.
param htmlFormat - Boolean flag to enable/disable html message result.
The default value is false.
void setHTMLMessage(bool htmlFormat);Enable/disable plain text message result.
param textFormat - Boolean flag to enable/disable plain text message result.
The default value is true.
void setTextMessage(bool textFormat);Set the maximum message to search.
param limit - Any number from 0 to 65535.
The default value is 20.
void setSearchLimit(uint16_t limit);Enable/disable recent sort result.
param recentSort - Boolean flag to enable/disable recent message sort result.
The default value is true.
void setRecentSort(bool recentSort);Assign callback function that return status of message fetching or reading.
param readCallback - The function that accept readStatusCallback as parameter.
void setReadCallback(readStatusCallback readCallback);Enable/disable attachement download progress while fetching or receiving message.
param report - Boolean flag to enable/disable attachement download progress while fetching or receiving message.
To get the download status, Callback function should be set via setReadCallback.
void setDownloadReport(bool report);Determine only message header is return when search.
bool isHeaderOnly();Get the sender name/Email for selected message from search result.
param messageIndex - The index of message.
return Sender name/Email String.
String getFrom(uint16_t messageIndex);Get the sender name/Email charactor encoding.
param messageIndex - The index of message.
return Sender name/Email charactor encoding which use for decoding.
String getFromCharset(uint16_t messageIndex);Get the recipient name/Email for selected message index from search result.
param messageIndex - The index of message.
return Recipient name/Email String.
String getTo(uint16_t messageIndex);Get the recipient name/Email charactor encoding.
param messageIndex - The index of message.
return Recipient name/Email charactor encoding which use in decoding to local language.
String getToCharset(uint16_t messageIndex);Get the CC name/Email for selected message index of IMAPData result.
param messageIndex - The index of message.
return CC name/Email String.
String getCC(uint16_t messageIndex);Get the CC name/Email charactor encoding.
param messageIndex - The index of message.
return CC name/Email charactor encoding which use in decoding to local language.
String getCCCharset(uint16_t messageIndex);Get the message subject for selected message index from search result.
param messageIndex - The index of message.
return Message subject name/Email String.
String getSubject(uint16_t messageIndex);Get the message subject charactor encoding.
param messageIndex - The index of message.
return Message subject charactor encoding which use in decoding to local language.
String getSubjectCharset(uint16_t messageIndex);Get the html message for selected message index from search result.
param messageIndex - The index of message.
return The html message String or empty String upon the setHTMLMessage was set.
String getHTMLMessage(uint16_t messageIndex);Get the plain text message for selected message index from search result.
param messageIndex - The index of message.
return The plain text message String or empty String upon the setTextMessage was set.
String getTextMessage(uint16_t messageIndex);Get the html message charactor encoding.
param messageIndex - The index of message.
return Html message charactor encoding which use in decoding to local language.
String getHTMLMessgaeCharset(uint16_t messageIndex);Get the text message charactor encoding.
param messageIndex - The index of message.
return The text message charactor encoding which use in decoding to local language.
String getTextMessgaeCharset(uint16_t messageIndex);Get the date of received message for selected message index from search result.
param messageIndex - The index of message.
return The date String.
String getDate(uint16_t messageIndex);Get the message UID for selected message index from search result.
param messageIndex - The index of message.
return UID String that can be use in setFetchUID.
String getUID(uint16_t messageIndex);Get the message number for selected message index from search result.
param messageIndex - The index of message.
return The message number which vary upon search criteria and sorting.
String getNumber(uint16_t messageIndex);Get the message ID for selected message index from search result.
param messageIndex - The index of message.
return The message ID String.
String getMessageID(uint16_t messageIndex);Get the accept language for selected message index from search result.
param messageIndex - The index of message.
return The accept language String.
String getAcceptLanguage(uint16_t messageIndex);Get the content language of text or html for selected message index from search result.
param messageIndex - The index of message.
return The content language String.
String getContentLanguage(uint16_t messageIndex);Determine fetch error status for selected message index from search result.
param messageIndex - The index of message.
return Fetch error status.
bool isFetchMessageFailed(uint16_t messageIndex);Get fetch error reason for selected message index from search result.
param messageIndex - The index of message.
return Fetch error reason String for selected message index.
String getFetchMessageFailedReason(uint16_t messageIndex);Determine the attachment download error for selected message index from search result.
param messageIndex - The index of message.
return Fetch status.
bool isDownloadAttachmentFailed(uint16_t messageIndex, size_t attachmentIndex);Get the attachment download error reason for selected message index from search result.
param messageIndex - The index of message.
return Download error reason String for selected message index.
String getDownloadAttachmentFailedReason(uint16_t messageIndex, size_t attachmentIndex);Determine the downloaded/saved text message error status for selected message index from search result.
param messageIndex - The index of message.
return Text message download status.
bool isDownloadMessageFailed(uint16_t messageIndex);Get the attachment or message downloadeds error reason for selected message index from search result.
param messageIndex - The index of message.
return Downloaded error reason String for selected message index.
String getDownloadMessageFailedReason(uint16_t messageIndex);Assign the download and decode flags for html message download.
param download - Boolean flag to enable/disable message download.
return decoded - Boolean flag to enable/disable html message decoding (support utf8 and base64 encoding).
void saveHTMLMessage(bool download, bool decoded);Assign the download and decode flags for plain text message download.
param download - Boolean flag to enable/disable message download.
return decoded - Boolean flag to enable/disable plain text message decoding (support utf8 and base64 encoding).
void saveTextMessage(bool download, bool decoded);Determine the mailbox folder count.
return Folder count number.
uint16_t getFolderCount();Get the mailbox folder name at selected index.
param folderIndex - Index of folder.
return Folder name String.
Use folder name from this function for fetch or search.
String getFolder(uint16_t folderIndex);Determin the number of supported flags count.
return Flag count number.
uint16_t getFlagCount();Get the flag name for selected index.
param folderIndex - Index of folder.
return Flag name String.
Use flags from this function for fetch or search.
String getFlag(uint16_t flagIndex);Get the number of message in selected mailbox folder.
return Total message number.
size_t totalMessages();Get the number of message from search result.
return Search result number.
size_t searchCount();Get the number of message available from search result which less than search limit.
return Available message number.
size_t availableMessages();Get the number of attachments for selected message index from search result.
param messageIndex - Index of message.
return Number of attachments
size_t getAttachmentCount(uint16_t messageIndex);Get file name of attachment for selected attachment index and message index from search result.
param messageIndex - Index of message.
param attachmentIndex - Index of attachment.
return The attachment file name String at the selected index.
String getAttachmentFileName(size_t messageIndex, size_t attachmentIndex);Get the name of attachment for selected attachment index and message index from search result.
param messageIndex - Index of message.
param attachmentIndex - Index of attachment.
return The attachment name String at the selected index.
String getAttachmentName(size_t messageIndex, size_t attachmentIndex);Get attachment file size for selected attachment index and message index from search result.
param messageIndex - Index of message.
param attachmentIndex - Index of attachment.
return The attachment file size in byte at the selected index.
int getAttachmentFileSize(size_t messageIndex, size_t attachmentIndex);Get creation date of attachment for selected attachment index and message index from search result.
param messageIndex - Index of message.
param attachmentIndex - Index of attachment.
return The attachment creation date String at the selected index.
String getAttachmentCreationDate(size_t messageIndex, size_t attachmentIndex);Get attachment file type for selected attachment index and message index from search result.
param messageIndex - Index of message.
param attachmentIndex - Index of attachment.
return File MIME String at the selected index e.g. image/jpeg.
String getAttachmentType(size_t messageIndex, size_t attachmentIndex);Clear IMAPData object data.
void empty();Set SMTP server login credentials
param host - SMTP server e.g. smtp.gmail.com
param port - SMTP port.
param loginEmail - The account Email.
param loginPassword - The account password.
param rootCA - Root CA certificate base64 string
void setLogin(const String &host, uint16_t port, const String &loginEmail, const String &loginPassword);
void setLogin(const String &host, uint16_t port, const String &loginEmail, const String &loginPassword, const char *rootCA);
Set STARTTLS mode to enable STARTTLS protocol.
param starttls - bool flag that enables STARTTLS mode
void setSTARTTLS(bool starttls);Set debug print to serial.
param debug - bool flag to enable debug
void setDebug(bool debug);Set Sender info
param fromName - Sender's name
param senderEmail - Sender's Email.
void setSender(const String &fromName, const String &senderEmail);Get Sender's name
return Sender's name String.
String getFromName();Get Sender's Email.
return Sender's Email String.
String getSenderEmail();Set Email priority or importance
param priority - Number from 1 to 5, 1 for highest, 3 for normal and 5 for lowest priority
void setPriority(int priority);Set Email priority or importance.
param priority - String (High, Normal or Low)
void setPriority(const String &priority);Get Email priority
return Number represents Email priority (1 for highest, 3 for normal, 5 for low priority).
uint8_t getPriority();Add one or more recipient
param email - Recipient Email String of one recipient.
To add multiple recipients, call addRecipient for each recipient.
void addRecipient(const String &email);Remove recipient
param email - Recipient Email String.
void removeRecipient(const String &email);Remove recipient
param index - Index of recipients in Email object that previously added.
void removeRecipient(uint8_t index);Clear all recipients
void clearRecipient();Get one recipient
param index - Index of recipients.
return Recipient Email String at the index.
String getRecipient(uint8_t index);Get number of recipients
return Number of recipients.
uint8_t recipientCount();Set the Email subject.
param subject - The subject.
void setSubject(const String &subject);Get the Email subject.
return Subject String.
String getSubject();Set the Email message
param message - The message can be in normal text or html format.
param htmlFormat - The html format flag, True for send the message as html format
void setMessage(const String &message, bool htmlFormat);Get the message
return Message String.
String getMessage();Determine message is being send in html format.
return Boolean status.
bool htmlFormat();Add Carbon Copy (CC) Email.
param email - The CC Email String.
void addCC(const String &email);Remove specified Carbon Copy (CC) Email
param email - The CC Email String to remove.
void removeCC(const String &email);Remove specified Carbon Copy (CC) Email
param index - The CC Email index to remove.
void removeCC(uint8_t index);Clear all Carbon Copy (CC) Emails
void clearCC();Get Carbon Copy (CC) Email at specified index.
param index - The CC Email index to get.
return The CC Email string at the index.
String getCC(uint8_t index);Get the number of Carbon Copy (CC) Email.
return Number of CC Emails.
uint8_t ccCount();Add Blind Carbon Copy (BCC) Email
param email - The BCC Email String.
void addBCC(const String &email);Remove specified Blind Carbon Copy (BCC) Email
param email - The BCC Email String to remove.
void removeBCC(const String &email);Remove specified Blind Carbon Copy (BCC) Email
param index - The BCC Email index to remove.
void removeBCC(uint8_t index);Clear all Blind Carbon Copy (BCC) Emails
void clearBCC();Get Blind Carbon Copy (BCC) Email at specified index.
param index - The BCC Email index to get.
return The BCC Email string at the index.
String getBCC(uint8_t index);Get the number of Blind Carbon Copy (BCC) Email
return Number of BCC Emails.
uint8_t bccCount();Add attchement data (binary) from internal memory (flash or ram).
param fileName - The file name String that recipient can be saved.
param mimeType - The MIME type of file (image/jpeg, image/png, text/plain...). Can be empty String.
param data - The byte array of data (uint8_t).
param size - The data length in byte.
void addAttachData(const String &fileName, const String &mimeType, uint8_t *data, uint16_t size);Remove specified attachment data.
param fileName - The file name of the attachment data to remove.
void removeAttachData(const String &fileName);Remove specified attachment data.
param index - The index of the attachment data (count only data type attachment) to remove.
void removeAttachData(uint8_t index);Get the number of attachment data.
return Number of attach data.
uint8_t attachDataCount();Add attchement file from SD card
param fileName - The file name String that recipient can be saved.
param mimeType - The MIME type of file (image/jpeg, image/png, text/plain...). Can be omitted.
void addAttachFile(const String &filePath, const String &mimeType = "");Remove specified attachment file from Email object.
param fileName - The file name of the attachment file to remove.
void removeAttachFile(const String &filePath);Set storage type for all attach files.
param storageType - The storage type to read attach file, MailClientStorageType::SD or MailClientStorageType::SPIFFS.
void setFileStorageType(uint8_t storageType);Remove specified attachment file.
param index - The index of the attachment file (count only file type attachment) to remove.
void removeAttachFile(uint8_t index);Clear all attachment data.
void clearAttachData();Clear all attachment file.
void clearAttachFile();Clear all attachments (both data and file type attachments).
void clearAttachment();Get number of attachments (both data and file type attachments).
return Number of all attachemnts.
uint8_t attachFileCount();Add one or more custom message header field.
param field - custom header String inform of FIELD: VALUE
This header field will add to message header.
void addCustomMessageHeader(const String &field);Remove one custom message header field that previously added..
param field - custom custom message header field String to remove.
void removeCustomMessageHeader(const String &field);Remove one custom message header field that previously added by its index.
param index - custom message header field index (number) to remove.
void removeCustomMessageHeader(uint8_t index);Clear all ccustom message header field that previously added.
void clearCustomMessageHeader();Get the number of custom message header field that previously added.
return Number of custom message header field.
uint8_t CustomMessageHeaderCount();Get custom message header field that previously added by index.
param index - The custom message header field index to get.
return The custom message header field string at the index.
String getCustomMessageHeader(uint8_t index);Clear all data from Email object to free memory.
void empty();Set the Email sending status callback function to Email object.
param sendCallback - The callback function that accept the sendStatusCallback param.
void setSendCallback(sendStatusCallback sendCallback);