SMTP Not Working After Migration to New Server

We migrated SuiteCRM to a new server. SMTP settings were working before but now emails fail silently. No errors in logs. What could be the problem?
I don’t know what I am missing here.

This might help you get more information:

@pgr suggestion is a good one to get specific info, but here are a few things I would check in addtion:

  1. PHP version is correct
  2. PHP memory limit it correct
  3. PHP options required are enabled.
  4. PHP time limit
  5. Your server allows outbound SMTP connections (fire wall)
  6. Your host allows SMTP connections through their relay
  7. Your SPF records are configured properly to allow new IP of new server
  8. You have your email routing configured properly in WHM (if you’re using WHM/Cpanel)
  9. You have transport=dkim_remote_smtp setup if using WHM/Cpanel in tweak settings.
  10. Your new host may have different SMTP ports.

Those are my top 10.