Your email infrastructure is an important piece or your email reputation. Most ISPs now require that email senders use some form of authentication to ensure delivery-- think of it as Caller ID for email. If the ISP knows you are who you say you are, it is the first step to email delivery (though it does not alone get your email delivered). Email authentication has two primary benefits: it prevents the forgery of email messages and allows senders to build a positive reputation with receivers based upon their mailing behavior.
If you are not using an email authentication protocol, you need to research which one is right for you and get started. You can find detailed information about the three dominant schemes on the following websites:
Make sure that when you implement authentication, you do so for all of your corporate email-- consider email you send internally, through third parties, transactional email, marketing email, et cetera. Once you have all your email sources authenticated, you need to test your records to make sure they are set up correctly. Here are some easy testing resources:
In addition to proper authentication, you need to also pay attention to these infrastructure items:
- Use a reverse DNS record
- Have a "round trip" reverse DNS
- Bounce address accepts mail (and has MX record)
- Postmaster and abuse addresses that accept mail