With so many available options for email accounts, it is extremely likely that you have more than one email account.
At MIT, there are many users who have their MIT account forwarded to another email address, or vise versa.
As such, you may want to give your mobile device the ability to choose which email account you would like to send, or reply to, an email from. This is an ability that your mobile device should have, as long as you setup the accounts on your mobile device previously.
When you send or reply to an email message, just click on the "From" field when replying to or sending an email. It should reveal a drop down menu that allows you to change what account the message is coming from.
For example, say you have 2 accounts, email@example.com & firstname.lastname@example.org, and you forward your MIT email to your GMAIL account. Your mobile device has the ability to reply to an email in your GMAIL account as if it coming from your MIT email, as long as you setup both accounts ( email@example.com & firstname.lastname@example.org ) on your mobile device first. Just change the email address in the “From” field. That's all you have to do.