can't send emails

Avast Free Antivirus / Premium Security
1

I have a friend who has avast on their computer. They have 2 email accounts and use outlook express. One account works fine but the other one has real problems sending mail. Usually this message appears
Your server has unexpectedly terminated the connection. Possible causes for
this include server problems, network problems, or a long period of inactivity.

There was an error code but they somehow didn’t send that bit to me. we spoke to the mail provider who thought it would be a antivirus/firewall problem. Obviously using avast antivirus and usuing the windows sp2 firewall. Whatever we try we can’t sort it out. We tried disabling all of vast but still no joy. Any suggestions greatly appreciated. Thanks

2

Without the error text it will be somewhat difficult to guess what the problem is, get him to replicate the error again and have him copy and paste the complete error text to you.

Do any of those accounts use SSL or TLS (secure encrypted) email ?
What are the email ports used (Tools, accounts, select the problem account, properties, advanced, see image.