That is a pretty poor way to way to setup a different e-mail address to send through gmail! They way you've done it, it will always say "Sent on behalf of" then say the original g-mail address!!! That sucks and looks unprofessional when you are trying to use a professional e-mail domain like
me@mycompany.com 
To set it up FLAWLESSLY to send mail through gmail using a non-gmail address without the "on behalf of" do the following:
In your gmail account, click the gear icon in the top right, then settings.
Click on accounts and import, then click "Add another email address you own"
Type your name and the
other e-mail address you want to use, I'll use
joe@blow.com for this example.
UNCHECK "treat as alias", click next.
This is where my solution differs from the one above. Click "Send through blow.com SMTP servers".
For SMTP server use: smtp.gmail.com
Username:
myaccount@gmail.com (this is your real/main gmail e-mail address)
Password: your gmail password.
Don't adjust any other settings and click Next. If you got your gmail e-mail address and password correct it should say "Congratulations, we successfully blah blah..." and will ask you for to verify a confirmation code.
DO NOT CLOSE THIS SCREEN!
Check your e-mail at your new address (i.e. my
joe@blow.com one) and you should have a message called "Gmail Verification, send mail as
joe@blow.com". Either click the "confirm your request" link in the e-mail, or what I like to do is copy the "confirmation code" and paste it in the verify box back over at the gmail window and click verify.
DONE!
Now you should be back at your gmail settings screen. Your newly added email address will show up there. You can click "make default" to make it ALWAYS show this address when sending mail (super handy if using GMAIL as a SMTP or smart host relay for your server!) or otherwise when sending mail you can just drop down the "from" box and pick this address when you need it.
Tada! No more "sent on behalf of..." sweeeeeeeet.
-Jamie M.
MODS: All of the above information was discovered by ME, written by ME, using no other sources.
