How We Handle Mail Services
There is SMTP on each server so that your code can send outbound mail. There is no need to set properties - the JavaMail defaults will handle everything under the hood. If you are using a framework or must otherwise set properties, they're mail.smtp.host=localhost and mail.smtp.port=25 .
Authentication is not used (mail is only accepted from localhost). There are no limits as to how much mail you may send so long as you do not engage in spamming which is strictly prohibited.
We do not run POP on the servers. It's inefficient and there's a better way to have vanity addresses (you@your_domain) .
Rather than having to check multiple mailboxes, set up forwards so that mail for you@your_domain (and sales@, admin@, etc.) ends up in the you@your_regular_mailbox.
You do that from your domain registrar's control panel. Most domain registrars provide mail forwarding for free. If yours does not, contact us and we will setup forwarding for you.
We use the above system and take it one step further. By using a GMail account as an IMAP intermediary, we basically have an Exchange Server for free. If you interested in doing that, contact us for a free "how to".