SMTP timeout after sending data block (# bytes written): Connection timed out

Symptoms

There is an SMTP timeout with an error similar to the following:

CONFIG_TEXT: SMTP timeout after sending data block (106457 bytes written): Connection timed out

Cause

This can be caused by firewall and/or network issues.

Resolution

• Whitelist the mail servers' IPs in each respective firewall.
• Contact your network provider/administrator and possibly the other mail server's network administrator, and have them troubleshoot any network connectivity issues between the servers.