What Is Causing This Error?
The error arises because the SMTP server rejects connections on port 465. Since port 465 is an outdated standard for SMTP, it’s common for SMTP servers to not support connections through this port anymore.
Resolving the Error – Solution
To solve this issue, switch to using port “587” or “2525” for making SMTP connections with TLS. Port “2525” should be considered an alternative only if port 587 is inaccessible and your SMTP server supports connections on this port.
That’s it! Now you know the common causes of SMTP error port 456 and how to resolve it.
If you’d like to learn how to troubleshoot other common errors, check out the following docs: