It’s nice to only have a single e-mail address, but for some people that’s just impossible. And instead of configuring multiple accounts for all e-mail addresses on your phone, you can forward all mail to a single account and receive and send using all e-mail addresses.
The native Google Mail mode on iOS (currently iOS 13.6) only allows sending as the primary e-mail address for the account, but there is a way around that. That way is IMAP mode, but we’ll also keep the native mode because it supports Contacts and Calendars syncing. And this works for both personal Gmail accounts and Google Apps (aka G Suite).
If you already have the native mode configured on your iPhone, we’ll just deactivate the E-mail syncing by going to
Settings > Password & Accounts > [Account Name]
and deselecting the Mail option as in the print screen to the right.
Then add a new account of type Other > Add Mail Account
To be able to use your account as IMAP, you either need to allow un-secure apps or enable 2 step authentication and add an App Password: https://myaccount.google.com/security
Then, in the web version of Gmail (https://mail.google.com), go to Accounts and Import and click Add Another E-mail Address. If that address is not part of the same G Suite account, you’ll be asked for a username and password. If using the Allow Unsecured Apps option (see above), then you’ll use your account’s password. Otherwise, if using 2-step authentication, use an App Password you’ll generate.
Now it’s time to test sending from your new e-mail aliases!
Enjoy and please share!