[Users] SMTP error when replying by email to Usenet posts

[Paolo Amoroso]

Thanks all, here are the answers to your questions.

Marco, I tried several times but the log doesn't provide any further
details.

Paul, I'm getting the log by clicking the "View log" button of the error
dialog Claws Mail displays. I can get the same log via the menu command
Tools > Netwok Log.

I think I enabled SMTP AUTH. In the dialog under Configuration >
Preferences for current account... > Account > Send I marked the "SMTP
Authentication (SMTP AUTH)" checkbox and left "Authentication method" to
Automatic. Are there other relevant settings?

The account credentials are correct and the connection dialog, as well
as the log, seem to suggest authentication succeeds but the issue occurs
later in the session.