While you have only one primary email address--the one you use to log into Gmail with--you may have several "alias" email addresses as well depending on what's been setup for you. You may also have an alternative address that you check that's a Google Group like info@ or hello@yourdomain.com
These so called "aliases" allow you to receive email sent to a different address in your primary mailbox. Similarly, with a little bit of setup, you can also send "from" an alias address.
Please note: an alias must be setup for you by an administrator before these instructions will work for you or you must already have access to the group address at groups.google.com.
Here's how to send from another address:
In Gmail, head to the "gear" icon and choose "settings."
At the top, click "Accounts" and click on "Add another email address."
In the pop-up window, enter your alias email address and, as appropriate, update your name (eg. ACME Corp Info) Make sure you leave the "treat as alias" box checked.
- Click "next step"
- Click "send verification"
- Check your email (or group email as appropriate) for the verification link and click on it.
- Click confirm
For good measure, you may want to set your preference whether you always reply from your default address or if you'd like to reply from the address the message was sent to. I prefer the latter. That simply means if the message was sent to Neil.Finn@ACMEcorp.com, my reply will come from that address. If it was sent to nfinn@ACMEcorp.com, my reply will come from that address.
Now when you compose an email, you can click your "from" address drop-down and select any alias you have setup and the message will go out from that address.
Happy emailing!