You may prefer to only work out of one email account, but have two or even three different accounts.
You need the ability to send mail as if you’re operating from multiple accounts, all from the same client.
You can do that in Gmail. To add a new sender account, head to Gmail, and then to the Settings page. Click on “Accounts and Import” up the top.
There, you’ll see the ability to “add another email address you own”. Click on that link, follow the prompts, and you’ll be ready to add a new address.