Winsock errors when using VPN
You are using VPN (Virtual Private Network) and the SMTP log shows entries like:
SMTP 21 Jul 99 12:33:37 F 3143 78248 winsock recv 10054 [18.104.22.168]
I started to see this when I’d opened a VPN connection from my server. Mail servers from within the address range of the VPN were returning these errors. I presume that you’d
get the same problem with a permenenly connected server which also had a RAS connection.
I solved it by ensuring that the VPN connection always requested a specific address, and adding that address to a nameserver as a lower priority MX record. The mail now gets through whether the VPN is connected or not.
Keywords:winsock, error, vpn