Smtp unauthorized use

After many years of AVG use and very effective protection(laptop/presently W-10), I started to get a lot of " undelivered mail " messages, apparently sent out of my outgoing mailbox to tens of different and unknown people. My server has changed my pass word once. A total scan was runned , resulting in 3     " troya"  files. Last version of AVG ( paid ) installed.
A few days latter, the same problem again !!!  Any suggestions ?

Hello Alfredo,

We request you to disable AVG protection temporarily by following the steps as mentioned in this article: http://avgread.me/1GnMD3N and check whether the issue persists.

Thanks much for your prompt reply. I decided on my own to block the sender as well as the server(right click the mail message) responsible for the spams and "undelivered mail" messages. I did not change my password either as previously suggested by my mail server. So far so good !(5 days). I will keep you posted.

Hello Alfredo,

We request you to disable AVG protection temporarily by following the steps as mentioned in this article: http://avgread.me/1GnMD3N and check whether the issue persists.

Thanks much for your prompt reply. I decided on my own to block the sender as well as the server(right click the mail message) responsible for the spams and "undelivered mail" messages. I did not change my password either as previously suggested by my mail server. So far so good !(5 days). I will keep you posted.