(really I'm not!)

1. Maybe because you misspelled something or are using text messaging shorthand, L337 (leet) speak or hacker jargon.

http://en.wikipedia.org/wiki/Text_messaging
http://en.wikipedia.org/wiki/L337

Anti-spam filters get suspicious when they see bad spelling or unusual characters inserted into words because this is what Spammers do all the time. Don't act like a Spammer and you won't get lumped in with them.

2. If you are at your corporate site you probably send e-mail out via your organization's mail server but when you work from home, at a hotel or at your favorite coffee spot they are probably either blocking outbound SMTP traffic to stop infected systems from sending Spam or are silently proxying port 25 'in your best interest'. This can cause your outbound e-mail to fail completely or fail something called an Sender Policy Framework (SPF) check or a domain check as an outgoing server whose name doesn't match your domain name raises a red flag, unless it's a well-known one, like Gmail or Yahoo.
 
What can you do about this?
 
A. Use webmail. Since you are connecting back to your real mail server the e-mail will not be blocked and it will be coming from your mail server so the mail server checks will pass. Make sure you use a secure connection (httpS) when you do this or the hotel or coffee shop may be able to read your e-mail. Not something to do if your working on your "super secret" plan!

B. Use a VPN to your office first then use your regular mail client. Again the e-mail is going from your laptop to your mail server first so you will pass these anti-spam checks. Some locations, like hotels, may not let you start a VPN connection so you will have to use webmail or the final solution - alternate SMTP port.

C. Use an alternate port for SMTP. Way back when the Internet was young and shiny and spammers weren't born things were a lot more permissive and so requiring people to identify themselves to send e-mail wasn't necessary. Today the best thing to do is run two SMTP services or e-mail server software that can listen for e-mail on more than one port. Leave port 25 to accept e-mail from the wild and do all your anti-spam checks on this port. The second port is going to be dedicated to accepting e-mail from your users only and therefore two things are needed:

1. An alternate port like 465 or 587 mapped through your firewall to your mail server.
2. A setting that forces your users to authenticate (provide a user name and password) FIRST before accepting e-mail from them.

This way your laptop connects to your mail server on a port that is not blocked and spammers can't use this port to send you spam because they don't have a username and password on your server - simple!
 
More about SPF records next week.

Shaun Sturby
Technical Services Manager
CudaMail