Originally Posted by alphasports
You have to figure that the average 1-page text-only email including headers is approx 20-30kb, so using your max of 100/day (200-300kb), you'd burn through your 10 Mb in about 10-12 days, conservatively maybe 15-20 days at most. That still leaves you with 10 days or more where they will no doubt hit you pretty hard with overage charges.
20-30kb per message? Not even close.
BlackBerry (BIS and BES) uses heavy compression which makes e-mail messages very very small. Your average email messages is typically around 1kb or less.
10MB for email only will last a very long time, even with a fair amount of attachments.