Yes - use Google Apps for Your Domain.
It's free for up to 50 users.
Free GAFYD (as provided by Tobbe below)
UPDATE This answer is no longer valid if you don't already have a Google Apps account. Google Apps is no longer free for new signups!! (Thanks to asalamon74 for the update)
The Email-SMS gateway that Google Voice uses formats email addresses like this in the messages that it sends to you:
12125551212.12015550189.{some-random-string}@txt.voice.google.com
The first phone number there is your own, the second is the other person in the conversation. The random string is just that, a bunch of letters, numbers, and punctuation with no apparent rhyme or reason.
However, this email address is re-usable. I just took a SMS message email that I'd received a couple of days ago and grabbed the address. Then I sent a new email message to that address and the recipient received it as a SMS message from my Google Voice number.
(You can't leave the random string out; it's probably some sort of hash to prevent random SMS sending.)
So, it's no help for the first time you send someone an SMS message, but if they send/reply to you (and you're using the Email-SMS gateway feature of Google Voice) you can save the address used to their contact record and can simply use email to send them SMS in the future.
Note: this only appears to work for the Gmail account associated with the Google Voice account sending the message. (Thank you Larry.)
Best Answer
Yes. Once you've set up another account in Gmail you can "send as" that account.
When you're composing an email message, the
From:
will now be a drop-down where you can choose the address you want to use.More information: Gmail Help: Send mail from a different address or alias