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Inconsistent SMTP Failure with Outlook

Thunderbird Connectivity
Matt replied
Magma_Flow
Magma_Flow

Greetings.

For many years I have used Thunderbird to send and receive mail through my Outlook account (while happily donating to Mozilla).

A few months ago, every initial attempt to send a message abruptly started to fail, generating the dreaded notice that “the message could not be sent because the connection to Outgoing server (SMTP) smtp-mail.outlook.com timed out.”

What is odd is that if I keep trying to send, the message always goes out eventually -- sometimes after only two tries, sometimes after ten tries.

Thus, my Outlook account works, my Thunderbird settings work, the SMTP server works -- but only at random intervals.

The problem has continued through several Thunderbird updates, including the current one (147.0.1). I tried changing the server to smtp.office365.com and got the same performance.

I am on MacOS 15.4 and am not running any third-party antivirus or firewall product.

My thanks to anyone who has insight into this problem.

Greetings. For many years I have used Thunderbird to send and receive mail through my Outlook account (while happily donating to Mozilla). A few months ago, every initial attempt to send a message abruptly started to fail, generating the dreaded notice that “the message could not be sent because the connection to Outgoing server (SMTP) smtp-mail.outlook.com timed out.” What is odd is that if I keep trying to send, the message always goes out eventually -- sometimes after only two tries, sometimes after ten tries. Thus, my Outlook account works, my Thunderbird settings work, the SMTP server works -- but only at random intervals. The problem has continued through several Thunderbird updates, including the current one (147.0.1). I tried changing the server to smtp.office365.com and got the same performance. I am on MacOS 15.4 and am not running any third-party antivirus or firewall product. My thanks to anyone who has insight into this problem.

Modified by Magma_Flow

All Replies (2)

Magma_Flow
Magma_Flow Question owner

I have discovered an apparent workaround that may benefit others with the same problem.

After clicking Send on a message, you get a progress bar. Instead of waiting and hoping that the progress bar does not end once again in SMTP failure, initiate a POP connection by telling Thunderbird to get new messages for the current account.

In my tests, the command to get new messages immediately triggers a successful SMTP connection, causing the outgoing message to be sent.

Matt
Matt
  • Top 25 Contributor

Your resolution in practice is about the same as using your browser to go to youtube and also google.com at the same time and saying going to one fixes your connection to the other. There is no real relationship other that a probable software issue that your action causes to wake-up and smell the coffee I look to antivirus and VPN as they are the most common points of failure in any connection or timeout issue these days.

It is entirly possible that your are connecting to outlook to frequently. Especially if you have that same account configured in your tablet or phone. Outlook.com has always been touchy about connection frequency. I find most of my outlook accounts do not get mail on startup. I have to wait until they trigger a check after 10 minutes or so and they just get mail. But having the connections for multiple accounts simultaneously causes failure.

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