"Jon":http://www.jonbruck.com/ convinced me a while back to move all my email to Gmail, since its easier to archive and search ( Gmail rocks at this ). I had to format my laptop a while back because I removed some libs that made the entire system unstable.
Another reason for moving all my mail to Gmail was to reduce SPAM. On a good day I get about 200 SPAM mails. Mail.app did a pretty good job of reducing this to about 50. This number reduced to 2-5 once I started piping it through Gmail.
Now because I had moved all my mail to Gmail, I did not have to bother backing up all my emails, because Gmail already had them archived for me. I have one gmail account which I use for my free software and consulting address. I spent a good number of hours trying to figure out how to get Mail.app to use multiple addresses with a single Mail.app account.
At first I thought I could check out Thunderbird since its opensource, I could just hack the source code and integrate it with the MacOSX's Addressbook.app. But then I would also have to hack it to support multiple email addresses per account. Once I weighed all the pros and cons, It seemed to be smarter to hack Mail.app through Apple Script or write a Proxy for my outgoing mail in Ruby.
Finally I figured it out. What if i just entered a bunch of email addresses seperated by commas (like you normally do when you want to send it to multiple people) in the Email setup? Would it work? Yes! It did work!
Here is a small tute on backing up your mail at Gmail and using it with Mail.app. If you have already setup Gmail to support multiple email addresses you can just skip to the second section.
