I am experiencing same issue. Only way to receive my messages is to turn off avast for 10 minutes and turn it back on.

Well having that said … Maybe its not same since I actually have problem with 110 port and pop3. But its similar.

“NB connect error 1460”

[Edit]
And with sending:
Service not available, closing transmission channel. The server response was: Cannot connect to SMTP server [IPADDRESSANDPORT], NB connect error 1460