While most people realize they can send text messages via a carrier's
email gateway, most don't realize that they can send multimedia messages 
as well. Many carriers have two separate email domains; one for SMS and one 
for MMS. Others use the same email domain for both. Sending MMS has several 
advantages. First, the character-count limits which exist for SMS messages 
(which vary by carrier) don't exist for mms messages. Second, you can attach 
pictures or sound files to your email messages (the same way you'd attach them 
when sending to regular email addresses), and your customers will be able to 
receive them along with your text message. Note that different carriers have 
different requirements for pictures, and if a picture doesn't meet the 
criteria, it won't get displayed.  We've found that making your jpg file as 
small as possible is important (Linux users: convert -quality 2 inputfile 
outputfile). Also, we've found that 320x240 pixels seems to work well for 
most carriers.