1. Spam filters!
2. Free backups of my mail
3. Can access all my email no matter where I am

I forward all my email addresses on to Gmail.

You can also set up Thunderbird / outlook to connect to Gmail, should you so choose.

Check out the Gmail power usage guide for details.

Tips:

1) While looking into Mozilla Jetpack I came across the better Gmail checker. This neat little thing puts a little icon in the lower right corner of your Firefox with the number of unread Gmails in your inbox.

This lead me to finally sort out the 1100 unread emails in my Gmail. Most of them are email lists etc, that I have no intention of reading and figuring out how to mark all of them read had put me off ever doing so.

Anyway, inspired by my new jetpack toy, I went about figuring that out too:
2) To mark all mail read:

• In the search box, type “is:unread”
• In the select area press “All”
• A link will appear that says “Select all conversations that match this search”, press it
• From the drop down, select “Mark All as Read”.

So there you have it, happy Gmailing everybody!