Problem Description
When sending a message to a Websavers hosted email account:
- The bounce might say: 602 Attempted to send the message to the following IPs: [the_server_ip]
- The bounce will likely say: Action: failed Status: 5.0.0
This may indicate an SSL certificate verification problem.
Problem Resolution
If you're using a free Let's Encrypt SSL certificate, you can resolve this by re-issuing the SSL certificate for the domain and ensuring it applies to the mail.<domain> subdomain. This is one of the checkboxes available to you when issuing the certificate. Here's how to re-issue a Let's Encrypt certificate.
Note: you may also wish to chat with the sending server admins as many servers do not have matching SSL certificates on their listed MX records. While certificate validation is commendable from a security perspective, it's very likely to also run up against many MX records that do not validate, and so best-effort would ensure wider compatibility.
