Make sure to check your SPAM folder regularly

Depending on your e-mail client, you may be missing some important e-mails because they're getting filtered as SPAM. SPAM filters continue to evolve and different e-mail systems use different tactics. In the past, filters would look for certain keywords. Now, if you're a health care professional and you're sending an e-mail describing certain body parts (sexual parts such as breast, penis, etc.), then your e-mail address could get flagged as a SPAMMER! Well, those were the old days. Some filters still operate like that, but I'd say fewer tend to use that system. Then we have services like the DCC (Distributed Checksum Clearinghouses), SPF (Sender Policy Framework), DomainKeys, and DKIM (DomainKeys Identified Mail). Wow, did you catch all that?

The bottom line is that filtering SPAM is an evolving process. What used to work 3 years ago probably won't work today. No SPAM filter is perfect, so you're probably losing a few important e-mails each week because they're getting stuck as SPAM.