sendmail with a 'different' SMTP host solution : pro and cons

What are 开发者_JAVA百科the pro and cons of using the SMTP host option of my choice? Do sending mails from localhost require a specific SMTP host? Is there any discernible difference on the receiving end between a mail sent via the server where the site resides and a dedicated mail server?

thanks

Luca

This depends if localhost refers to a public server with a proper DNS and reverse DNS entry, or if localhost is a machine you operate from a residential Internet Service Provider.

If localhost is a real server, outbound mails may be delivered a little faster if sent from the same server, and configuration in PHP & others is generally a lot simpler to setup.

If it isn't a proper server though, especially having proper DNS entries, the likelihood of much mail from it actually reaching recipients is low. Most receiving SMTP servers will reject mail if they cannot validate the source via a reverse DNS entry.

If you use a dedicated mail server, you get the benefit of all the inbound & outbound logging being on the same machine, and when receiving SMTP hosts lookup your domain's MX record in DNS, it will already be configured as the mail server rather than the web server. But this just requires a little more configuration on the web server, especially if the mail server requires authentication from the web server rather than treating it as a trusted relay sender.