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Sending emails in Thunderbird

  • 2 replies
  • 0 have this problem
  • 15 views
  • Last reply by john1180

john1180
john1180
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Hello, I have Thunderbird 115 on a Win10 HP laptop. Until today, I could both send and receive emails OK; today, I can only receive emails, for some unknown reason I have an error message with sending only, reading: "Sending of the message failed. The message could not be sent because connecting to Outgoing server (SMTP) smtp.fastmail.com failed. The server may be unavailable or is refusing SMTP connections. Please verify that your Outgoing server (SMTP) settings are correct and try again." The SMTP settings match what is on Fastmail's website for POP3. I haven't done anything I can think of since last using Thunderbird that would trigger this. I have updated successfully to Thunderbird 128 OK and that hasn't solved the problem. The email provider is Fastmail (I've been in touch with them, they have given advice, so far, no luck), SMTP settings are on the attached image. The ISP is NBN (National Broadband Network). Antivirus software is McAfee Premium - Individual. It is really frustrating.

Hello, I have Thunderbird 115 on a Win10 HP laptop. Until today, I could both send and receive emails OK; today, I can only receive emails, for some unknown reason I have an error message with sending only, reading: "Sending of the message failed. The message could not be sent because connecting to Outgoing server (SMTP) smtp.fastmail.com failed. The server may be unavailable or is refusing SMTP connections. Please verify that your Outgoing server (SMTP) settings are correct and try again." The SMTP settings match what is on Fastmail's website for POP3. I haven't done anything I can think of since last using Thunderbird that would trigger this. I have updated successfully to Thunderbird 128 OK and that hasn't solved the problem. The email provider is Fastmail (I've been in touch with them, they have given advice, so far, no luck), SMTP settings are on the attached image. The ISP is NBN (National Broadband Network). Antivirus software is McAfee Premium - Individual. It is really frustrating.
Attached screenshots

Chosen solution

Antivirus software is McAfee Premium

McAfee may well be the problem.

Try to start Windows 10 in safe mode with networking enabled.

Does the problem go away?

Windows safe mode disables anti-virus software. This is a troubleshooting step, not a solution.

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christ1
christ1
  • Top 25 Contributor
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Chosen Solution

Antivirus software is McAfee Premium

McAfee may well be the problem.

Try to start Windows 10 in safe mode with networking enabled.

Does the problem go away?

Windows safe mode disables anti-virus software. This is a troubleshooting step, not a solution.

Helpful?

john1180
john1180 Question owner
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Yes, it did turn out that McAfee was the problem. I was swapping emails with Fastmail support and after some testing, the problem turned out to be McAfee's VPN; turning this off meant that I could send emails OK. Fastmail's support then provided alternate SMTP / port options to work with firewalls, and once these settings were updated in Thunderbird, I could send emails OK again with the McAfee VPN on. Regards, John

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