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550 Maximum line length exceeded (see RFC 5322 2.1.1) send error after upgrading to TP 91.1.1

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Yesterday I upgraded TB to v91.1.1 and since the upgrade I have been unable to send HMTL formatted emails via Thunderbird (can still send plain text). The diagnostic code from the sending server is:

Diagnostic-Code: smtp; 550 Maximum line length exceeded (see RFC 5322 2.1.1).

I haven't had any issues with TB previous versions (have been using TB for about 30 years) and it is the first time I have struck the error after an update to TB.

I have uninstalled TB and reinstalled the latest version - this made no difference.

Does anyone know if this is a bug with the current version where it is creating extra long line lengths in the send code?

Yesterday I upgraded TB to v91.1.1 and since the upgrade I have been unable to send HMTL formatted emails via Thunderbird (can still send plain text). The diagnostic code from the sending server is: Diagnostic-Code: smtp; 550 Maximum line length exceeded (see RFC 5322 2.1.1). I haven't had any issues with TB previous versions (have been using TB for about 30 years) and it is the first time I have struck the error after an update to TB. I have uninstalled TB and reinstalled the latest version - this made no difference. Does anyone know if this is a bug with the current version where it is creating extra long line lengths in the send code?

Chosen solution

The patch for bug 1729437 will hopefully appear in 91.1.2 next week.

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Cheers, I thought I was going a bit mad. I even tried resending HTML emails to myself that I had sent before the upgrade to TB 91.1.1 and they had the same notifications of failure to send.

Hopefully the bug is fixed promptly as I like some of the new features in 91.1.1...and don't particularly want to have to take the time to rollback to a previous version.

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Have tried the fix outlined above, but still having the same issues.

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Chosen Solution

The patch for bug 1729437 will hopefully appear in 91.1.2 next week.

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Thanks Guys, 91.1.2 has fixed the bug. Your quick response much appreciated.