Some Internet Providers such as PLDT and Globe Telecoms blocks SMTP (out going mail server) port 25 other than their own servers. If you are unable to send email using mail.yourdomain.com
using port 25
your can use the alternate settings.
- For shared Linux cPanel and Windows hosting, use alternate SMTP port 26
- For unlimited Windows hosting, use alternate SMTP port 2525
- For unlimited Linux hosting, use alternate SMTP port 587
If you are under a VPS plan or Dedicated Server, please request support to configure your server to accept SMTP connections from an alternate port