I am unclear on your statement. There is a test button, so I don't understand your issue.

i cant find a test button. i even asked chatgpt ;-) , the answer below:

In Mozilla Thunderbird, there is no direct "Test Connection" button in the Mail Account Settings dialog, as found in some other email clients. However, you can indirectly test the connection by ensuring the account settings are correct, and Thunderbird will attempt to connect to the mail server during its normal operations.

well, chatgpt is wrong. AI isn't perfect. click 'manual settings' on the setup page and the re-test button appears.

Cannot find a button "manual settings".

see attached

my original post was: hi all i miss a test connectivity button .....but when i have to edit something, i would like to test connectivity again in this dialog. Beside of this, Thunderbird is very useful to me and i support it with donations from time to time.

It's about editing existing accounts.

This is a user support forum, hence the assumption you are looking for help. If you have ideas or feedback I suggest you use the appropriate link. It can be found on the help menu in Thunderbird and points to https://connect.mozilla.org