Here's what you do:
- Setup a new account in Mail for your Gmail account, either as a Gmail account, or preferably using the Google-as-Exchange install method described here: http://www.powercx.com/iblog/ide… (Make sure to use the whole email address as your username, instead of cutting it off as you would with a standard gmail account)
- Send mail.
If you don't also want to check mail, or you want to set up a "send only" account, you just need to use fake entries for the receiving mail servers, and then use authenticated SMTP to your desired account(s)… You'll get an annoying error every time your iPad checks mail, but it'll work (I do this for my 4 domain aliases, and it's at least tolerable, if incredibly inefficient).
I have a personal email address (@mydomain.com) linked up to my GMail. I can send from it from web, but not from iPad's email app – can I change this?