Sorry - it was not me who wrote about proxy troubles.

My problem is: when sending EMails with Thunderbird, I often got timeouts from my GMX provider (timeout from SMTP-Server). When trying to send it once more, it mostly worked. But it’s annoying to send most mails two or three times.

After switching the Avast-scan for outgoing mails OFF it works now. With the problem you mentioned that malware can be sent without my knowledge.

Do you have a solution for this situation?