This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Thunderbird 115.10.1 (64-bit) fails to send SMTP messages

  • 5 replies
  • 1 has this problem
  • 1 view
  • Last reply by Matt

more options

Since Thunderbird was upgraded to 115.10.1 (64-bit), it now fails to send SMTP messages with the following error.

Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) ***.mail.pairserver.com was lost in the middle of the transaction. Try again.

This affects all six(6) accounts in Thunderbird, all of them can receive and edit e-mail messages; however, all of them fail to send e-mail messages.

Prior versions of Thunderbird have worked with this configuration for many years.

Other e-mail clients such as Evolution do not have this issue and I have confirmed with my provider that Thunderbird is no longer sending e-mails.

Any thoughts on how to roll back Thunderbird until this issue is resolved?

Since Thunderbird was upgraded to 115.10.1 (64-bit), it now fails to send SMTP messages with the following error. Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) ***.mail.pairserver.com was lost in the middle of the transaction. Try again. This affects all six(6) accounts in Thunderbird, all of them can receive and edit e-mail messages; however, all of them fail to send e-mail messages. Prior versions of Thunderbird have worked with this configuration for many years. Other e-mail clients such as Evolution do not have this issue and I have confirmed with my provider that Thunderbird is no longer sending e-mails. Any thoughts on how to roll back Thunderbird until this issue is resolved?

All Replies (5)

more options

Changing releases doesn't usually fix things -- but sometimes they do. The prior version is at https://ftp.mozilla.org/pub/thunderbird/releases/115.10.0/ or you could upgrade to 115.11.

Helpful?

more options

Thanks; however, sudo apt install thunderbird indicates: thunderbird is already the newest version (1:115.10.1+build1-0ubuntu0.23.10.1).

Helpful?

more options

Helpful?

more options

115.11.0 seems to resolve the SMTP issue.


Well, maybe not so much. I added back the additional accounts and it does not work again... Only supports a single account at the moment.

Modified by mozilla414

Helpful?

more options

This forum is full of folk using ubuntu that are not aware their new version 24 of the product is using sandboxed snap installs of applications which are causing all sorts of issue with remote anything really. See https://ubuntu.com/core/docs/security-and-sandboxing

Helpful?

Ask a question

You must log in to your account to reply to posts. Please start a new question, if you do not have an account yet.