Fix DOS issue on fixLineBuffer

[baptistejamin]

As explained on #64 , there is a DOS issue with the fixLineBuffer function.

This patch fixes the issue.

Since we couldn't catch the exact mail content creating this issue, I added a test script that creates a very long line email: #64 (comment)

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[titanism]

ping @andris9

[titanism]

The crisp folks fixing an issue we had for @forwardemail too, thanks many 🙏 🚀

[andris9]

@baptistejamin Thank you, but in order to merge the PR, I would have to ask you to sign the CLA as instructed in the comment above. If you are not able to, then let me know, and I'll implement a similar fix myself.

[baptistejamin]

@andris9 You can do whatever you want with the PR

[andris9]

Fixed in https://github.com/postalsys/mailauth/releases/tag/v4.6.9
I was not able to use the PR without a CLA, but I implemented a similar fix.