Transitioning to other email systems via Gmail
The auto-reply/auto-forward method works for MOST providers - Yahoo, Comcast, Verizon, etc. Where it doesn't work is AOL. I have actually used Gmail for a few of my customers to transition from AOL. AOL does not (as far as I know) provide any method for Forwarding. What I typically do is:
1 - Set up the new domain & email account - typically with a 3rd-party full-domain spam/virus filter (SpamStopsHere).
2 - Use Thunderbird to transfer all existing email from AOL to the new account via IMAP and remove the email from AOL. If done correctly, the folders and message timestamps will be preserved.
3 - Add a Gmail account and set it to automatically read AOL messages.
4 - Set the Gmail account to automatically forward all messages to the new account and then delete the messages.
5 - Set an auto-reply on AOL to let people know about the new email address.
6 - Set up the new email account access - depending on the user this might be webmail, Thunderbird, Outlook or something else. Of course, since the user has been using AOL for 20 years, some training may be required :-)
The beauty of this solution is that the user transitions from a large public system (AOL) to a private company or personal domain without losing any existing email messages and continuing to receive all messages in one location (except for the spam). Using Gmail directly would help some - e.g., much better spam filtering & searching - but would still not provide the, IMHO, major advantage of a proper domain with full control.
Gmail itself is a major improvement. With one of these customers he actually received notification from the intermediary Gmail account at one point because it detected viruses in new AOL messages and halted the automatic transfer. His domain filtering would have blocked the messages as well - but AOL didn't.