Timeout often appears when sending email

[Jason_Bassett]

Hello

My Office365 email address configured using IMAP is producing the following errors at times when trying to send email. I have both a Linux and Apple Mac laptop, both with latest Thunderbird, both with same issue:

"Sending of the message failed. The message could not be sent because the connection to outgoing server (smtp) smtp.office365.com timed out. Try again."

and

"Login to server smtp.office365.com failed." - Enter New Passoword/Cancel/Retry

These messages do not always occur. If I get the second message, I am able to keep hitting Retry until it eventually goes through.

I have been searching historic forum posts and found that increasing mailnews.tcptimeout may help - it did not.

Apparently there was another timeout setting available within the Edit > Preferences > Advanced > General area but this seems to no longer be the case.

Any ideas?

Regards

Jason

[DanRaisch]

Moving to Thunderbird Support.

Do you need to access the sent messages of that account from multiple computers? If that is not generally the case, try changing the target for saving sent messages to the Sent folder under Thunderbird's Local Folders account to see if the delay is due to the posting of the messages to the server.

[Jason_Bassett]

Hello DanRaisch

Yes I need to access all messages from either computer, and soon from yet more computers unfortunately.

For testing as per your recommendation I have changed the target for saving sent messages to the Sent folder under Thunderbird's Local Folders.

Issue with asking for password regularly is still prevalent.

Regards

Jason

[makaiguy]

Make sure any antvirus utility you may have installed is configured to NOT scan outgoing email messages. The delay added by such scanning can make server connections time out, especially with mime-encoded message attachments that must be decoded before they can be scanned.

[DanRaisch]

Although you are running Linux, do you have any security software running on that system?

[tanstaafl]

https://stackoverflow.com/questions/297 ... ing-oauth2 states that Office365 does not and will not support OAuth2 (an alternative to a password that both Outlook and Gmail support) despite the IMAP server telling an email client that it does, in its IMAP Capability response. That rules out experimenting with using a different authentication mechanism to workaround your problems.

https://productforums.google.com/forum/ ... eKIaO2ZF14 mentions somebody worked around a (non-Thunderbird related) Office365 problem by replacing smtp.outlook365.com with smtp.outlook.office365.com . Neither matches the smtp.office365.com that you are using. Could you post a link to the list of server settings that you think is appropriate? Its unclear to me what are the appropriate settings since there are "Office 365 for business or education, Office 365 Home, Office 365 Personal, or Office 365 University" and at least the business/education version appears to have different settings.