Cannot create an email of more than approx. 930 characters

[Herbert van Kampen]

Ubuntu: 20.04 LTS
Kernel: 5.13.0-40-generic
Thunderbird: 91.8.1 (64 bit)

Since starting service with an new ISP, I have been having problems with Thunderbird outgoing mail (incoming works fine). I did not see this problem with my previous ISP.

In both plain text and HTML formats, if the body of the email is greater than approx. 930 characters, when I click <Send>, the progress window goes to 100% sent, then hangs and eventually times out with the message not being sent. It shows an error message:

"Sending of message failed
The message could not be sent using Outgoing server for an unknown reason. Pleas verify that your Outgoing server settings are correct and try again."

I have contacted the new ISP about this and they have no idea what is causing this except it is not a problem with their SMTP host. All email settings are as directed by the new ISP.

I have confirmed this on 2 computers, both running the same software by creating messages with known character counts of over 1000 characters, created in a basic text editor, and progressively deleting characters until it is successfully sent and recounting the characters.

I do not see this problem on a Windows 10 machine using the same version of Thunderbird. I have also tried different email clients on Ubuntu and see the same issue.

I am at a loss, so any possible clues as to what is going on would be greatly appreciated.

[Herbert van Kampen (dimplecat)]

Hello:

I am unsure of what your message means; did you intend "ubuntu <>
thunderbird'?

Regardless, my question remains. As stated, my problem is not only
evident with thunderbird, but shows up in at least 3 other email
clients  (Evolution, Geary, Claws Mail). This would indicate the problem
is not with thunderbird, but with the SMTP processes.

Any ideas on the cause of this behaviour would be greatly appreciated.

Herbert van Kampen

On 2022-04-28 3:05 p.m., Erich Eickmeyer  wrote:
> ** Package changed: ubuntu => thunderbird (Ubuntu)
>

[Paul White (paulw2u)]

Herbert,

Erich's action was to assign your bug report to the Thunderbird package as the report was raised initially against the Ubuntu project in general. Ubuntu developers generally only subscribe to bug reports that they are responsible for rather than all Ubuntu bug reports. So it is essential that bug reports are targetted towards those than can really help with reported issues.

However, you did say that you are seeing this issue with four email clients so I agree that the problem is not with Thunderbird. If your mail provider has investigated the issue then they presumably are not at fault either. If this is still an issue then I would suggest a support site such as support forum of your local Ubuntu community http://loco.ubuntu.com/ or asking at https://askubuntu.com or https://ubuntuforums.org in order to ascertain the where the problem might lie. Moving this bug report, if the problem persists, to the problematic package will still be required should no-one else intervene in the meantime.

I see that the related question suggested contacting Mozilla. Did you do that and if so was any help forthcoming?

I'm moving this report back to the general Ubuntu pocket rather than invalidating it as you have confirmed you do not see this issue when using Windows 10 so still an Ubuntu issue.