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Suddenly cannot send mail from Thunderbird

Erling Agesen
Erling Agesen
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I use Thunderbird mail-client to acces my outlook.dk - account. It has run perfect for a period, but suddenly I cannot send e-mails !!

The error-txt is (translated from my danish version): Sending the message failed. The message could not be sent because the connection to the SMTP server smtp.office365.com timed out. Try again.

I expected that that a password should be entered before sending - but no ..... - only a long waiting periode and then the error-txt

Server-settings in Thunderbird are: IMAP-server: outlook.office365.com, IMAP port 993, IMAP-crypt.: TLS SMPT-server: smtp.office365.com, SMTP port 587, SMTP-crypt. STARTTLS, Auth: General password

This has troubled me for some time - help needed, thanks.

I use Thunderbird mail-client to acces my outlook.dk - account. It has run perfect for a period, but suddenly I cannot send e-mails !! The error-txt is (translated from my danish version): Sending the message failed. The message could not be sent because the connection to the SMTP server smtp.office365.com timed out. Try again. I expected that that a password should be entered before sending - but no ..... - only a long waiting periode and then the error-txt Server-settings in Thunderbird are: IMAP-server: outlook.office365.com, IMAP port 993, IMAP-crypt.: TLS SMPT-server: smtp.office365.com, SMTP port 587, SMTP-crypt. STARTTLS, Auth: General password This has troubled me for some time - help needed, thanks.

All Replies (4)

sfhowes
sfhowes
  • Top 10 Contributor
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Try with these settings:

incoming IMAP outlook.office365.com, 993, SSL/TLS security, OAuth2 authentication, User Name = email address

outgoing SMTP smtp.office365.com, 587, STARTTLS security, OAuth2 authentication, User Name = email address

https://support.mozilla.org/en-US/questions/1417298#answer-1588949

Enter the correct settings as above, remove the entries from Saved Passwords in Settings/Privacy & Security, accept cookies in Privacy & Security, restart TB, enter the account password in the OAuth window to allow TB access.

Erling Agesen
Erling Agesen Question owner
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Hi, I have changed IMAP settings and SMTP settings etc. according to instructions above. Still sending messages fail. "The message could not be sent because the connection to the SMTP server smtp.office365.com timed out. Try again."

I have 3 different mail-account on my TB, and on start of Thunderbird I am prompted to enter password for the two secondary account - but not my primary outlook account !

I am rather confused !

sfhowes
sfhowes
  • Top 10 Contributor
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First, make sure each account is sending on an smtp server that has the same User Name as the sending account:

https://support.mozilla.org/en-US/questions/1350593

What is the antivirus? If it's something like AVG/Avast, Norton, or any other non-Windows Security app, they are very often the cause of sending timeouts. Running Windows in safe mode, or removing (not disabling) the non-WS app, will test the possible effect of startup apps.

Erling Agesen
Erling Agesen Question owner
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I turned off AVAST MAIL SHIELD and am able to send mails from Thunderbird. At sending first time in a TB session I am asked for my password. So far everything runs smoothly.

I think it will be necessary to have the shild permanently turned off; it seems not possible to have an extension rel. to TB in the shield.

Thanks for your comments and advice.