Hello there we have read the question We try to help you

The use of multiple accounts is it here ? Do you use multiple accounts on the pc?and what email provider do you use? the same adres names has to be used by those account s and server but you cannot use the same users name for all account and servers please correct them.one user for the name per account of Thunderbird.

Then the SMTP settings has to be filled in correctly.

Can you send me a screenshot of this SMTP settings and setup accounts that s been used for that configuration tha t s recent now?

https://support.mozilla.org/en-US/kb/how-to-make-screenshots

Hello there

If you use Spam filters turn them off,having separated smtp servers for each account is a pre or must to.using the email addresses name s for each account and servers seperatly is Oke.The username of the account has to be the same for the first server and so on.

Greetings Firefox volunteer.

Hello there

Having problems to send some one some mail ask the other to check their settings if it s only having problems on that one person sending mail to them..and sending yourself a test mail is a good thing to check for further issues.

Greetings Firefox volunteer

Hi,

I do have multiple accounts, but they have different account names and incoming server settings.

I have 2 email accounts with DotEasy, apart from the above, the settings are identical. One works, one does not send to any email (or new ones).

Attached is a screen shot of the outgoing server settings.