Most mail servers protect their users from spam by a robust firewall and spam filter. That’s the good news.
The bad news is, sometimes they do that too efficiently so that they end up blocking the email that you would like to receive as well.
The solution is “whitelisting” such sources, that is, defining them as “good guys” wearing “white hats” so that your spam filter would not trash the mails arriving from that address.
But how do you whitelist an address? Since every mail server has different protocols and interface, there does not exisat one simple way to accomplish that.
So here is one of the most comprehensive whitelisting instructions that I’ve seen anywhere, courtesy of Steve Harrison.
It describes the way to whitelist email passing through the following sources:
ISPs — AOL, AOL Web Mail, Yahoo, Hotmail Live, Windows Live and MSN, Gmail, Earthlink, AT&T, Comcast.
Email Clients — Outlook 2003 (or higher), Mozilla Thunderbird, Blackberrys.
Spam Filters — Norton AntiSpam, McAfee Spamkiller,Cloudmark SpamNet, Mailblocks, MailShield, MailWasher, Oddpost, SpamAssassin, SpamButcher, Spameater Pro Spam Inspector, Spam Interceptor, SpamPal, Spam Sleuth.
And here is another great utility to generate your own whitelisting instructions — that is, instructions telling others how to whitelist the emails that you send to them: