- Plesk for Windows
Mails are not getting delivered from the server and got stuck in the outbound queue with the error:
Communications Error: Socket connection to alt4.gmail-smtp-in.l.google.com failed (error 10013). The host was either not contactable or it rejected your connection. Socket Family = 23; Host=1234:f8b0:400c:c03::1abcd; Port=25
It may be not possible to connect locally to SMTP port while service is running properly:
C:\> telnet 127.0.0.1 25
Connecting To 127.0.0.1...Could not open connection to the host, on port 25: Connect failed
Antivirus software is installed on the server.
Antivirus blocks connections to 127.0.0.1.
Configure corresponding exceptions in antivirus or remove it.