Hotmail for example doesn't like when you set up auto-forwarding to Gmail.
At least not last time I tried, it basically said "Sorry we don't like to do that" even though it has settings for auto-forwarding, I guess they don't like Gmail, which is understandable since they're competitors.
Other e-mail services might do the same thing. But Gmail is pretty amazing so there are ways to get around it, you can basically tell Gmail to log into your Hotmail or Yahoo (and maybe other places) and pick up your emails automatically every day, and they'll end up in your Gmail inbox. It will also pick up all your contacts and put them in the Gmail contacts folder, if you want.
It made the switching over a lot easier for me.
To do this, you:
- Log into your Gmail.
- Click the Settings icon in the top right corner
- Click the Accounts and Imports tab
- Click import from an email address
- Then you type in your (old) email that you want to pick up from.
- Continue, and type in the password you used for your old email inbox.
You can keep all the checkboxes selected if you want to get contacts (addressbook) as well as mails. Labels makes it easy to tell when you get an email in your Gmail inbox that was imported. It can be anything you want.
You can also learn to set up filters to organize your Gmail inbox like a pro (if you don't want the mails to show up in your normal inbox, maybe right below it in a special inbox, for example? Or maybe you want special mails to go into special folders automatically, so they don't clog up your inbox where you get important stuff.