Before Gmail came along I was looking for a way to consolidate all my email in a single location. I found some commercial services that would fetch mails from my other POP3 accounts and put them into a single inbox with IMAP access. Well now Gmail can do all that, faster, more reliably and for free!
In your GMail account in settings under 'Accounts and Import' you can set up accounts which you want mails to be fetched from. Google will check them once an hour and pop any new mails into your inbox. If you are in a hurry, you can also request a check right now from here. On the same page you can choose who to send mail as. Set up any additional accounts you might own and have other names you want to use.
For me this was all perfect. I got my current email addresses to redirect to my gmail address and I setup the identities so that I could mail from my gmail or other accounts. I used this system for my personal, gaming and work emails.
The whole point of this was to keep my gmail address hidden. So if I ever moved my email to another provider, I wouldn't need to tell anyone that my email address changed.
When I set everything up I check the settings by mailing myself - everything appeared just like I wanted it. But a few years later I saw an email I sent to someone on their computer in MS outlook. Accross the top of the message, instead of my name and email address, I saw this [My GMail address] on behalf of [my email address]. I was shocked, this is how my work emails have been going out for ages. And my gmail address wasn't supposed to be shown like that.
Turns out that many people have been complaining about this. Google always attach to the email in the sender field, your gmail email address to prevent problems with spam. And if the mail client the reciever is using shows the sender field (as outlook does) you will see this on behalf of nonsense.
