Messages are not sent any more because settings of SMTP server

Hello Merel, I'm Diane, a Microsoft 365 Apps & Services MVP and I'll try to help you today. Is incoming mail working correctly, only outgoing is not working, correct? Is this a new issue - did it work before and just stopped working? Do you have the most recent version of Thunderbird? Are you using the server settings shown in Outlook.com's Settings (gear icon) > View all Outlook settings > Mail > Sync email? Copy and paste the values from the Sync Email page. -- Diane Give back to the Community. Help the next person who has this issue by indicating if this reply solved your problem. Click Yes or No below.

Hello Diane,

Thank you for help. I will try to answer required information

"Is incoming mail working correctly, only outgoing is not working, correct? Is this a new issue - did it work before and just stopped working? "

The answer is yes to these 3 questions.

"Do you have the most recent version of Thunderbird?"

I downloaded recently the latest version 102.4.1 (64 bits) .
However checking the procedure to check the current version is confusing. I can't check it so far but I'm pretty sure.

"Are you using the server settings shown in Outlook.com's Settings (gear icon) > View all Outlook settings > Mail > Sync email? Copy and paste the values from the Sync Email page."

I'm working on that question. But please send me a link to that page.
That would show me the correct required settings. Thank you

By the way, have a look at the Dutch topic with the same issue :

This is the link to the Outlook.com settings page that lists the server names to use - https://outlook.live.com/mail/0/options/mail/accounts Your server names and port numbers should be the same as in the Thunderbird question you found... but the EN thread it points to doesn't have a clear solution, just discussion on which server names to use. :( >> I downloaded recently the latest version 102.4.1 (64 bits) . << That is the newest build - https://www.thunderbird.net/thunderbird/102.4.1/releasenotes/ Microsoft recently made some changes that should only affect business accounts trying to use POP or IMAP and SMTP but Thunderbird can handle the changes - so even if they messed up and consumer accounts are affected, it should work for you. What are you using for firewall and security software? If not defender, disable email scanning and see if that works.

• Should I install the English version of Thunderbird? It may be be easier for troubleshooting.

• I don't use security software. I understand that in such case Defender is automatically active.

• I don't use any particular software for firewall. Should I use one ?

• I have no steady standard browser. Often I change to compare.

• Screenshot of current settings here below. Note that option for incoming server there is no option for encryption mode TLS available. (only option SSL/TLS is available in the dropdown menu). I guess that those settings are ok.

The language version shouldn't matter - it sets the language of the interface. All languages use the same code for sending. Defender is fine for your security and firewall - it does not filter email like 3rd party security programs do (and will occasionally block mail to or from certain servers.) Browser doesn't matter either - most browsers are Chromium-based, except for Firefox. Your mail settings look good. Does incoming mail work and just sending fails? I'm going to install T-bird and test it - make sure it works and is not something specific to your computer.

I added the account to Thunderbird - same settings as you are using and no errors so far. How often do you have T-bird set to check for new mail? Try setting to it check between every 5 and 8 min. Removing the account and adding it back is one option.

I added the account to Thunderbird - same settings as you are using and no errors so far. How often do you have T-bird set to check for new mail? Try setting to it check between every 5 and 8 min. Removing the account and adding it back is one option.

You wrote : "I added the account to Thunderbird".
Which account (mail address) did you add ?

I focus only on *** Email address is removed for privacy *** I have more than one @hotmail.com accounts.
None of of those *** Email address is removed for privacy *** addresses can send.

Adjusting time for checking new mail is a task for tomorrow.

I used a live.com and outlook.com. I'll add a hotmail address and test - but the domain shouldn't matter. (Hope I don't prove that line wrong. :))