If you are getting the message “Cannot send mail, the sender address was invalid” and you’re using an iphone/Ipad/IOS device it is because you didn’t add a password when you added your outgoing mail settings. If you’re getting this message it means you’re going to have to enter your password. It is not optional.
Steps to fix issue:
- Go to settings on your iPhone/ipad/IOS device
- Under “Passwords & Accounts” look for the email address associated with this error message.
- Click on the account and if the options are grayed out, the email’s password must be reentered
- This will prompt you to reenter your password via an extra option present under the grayed out options.
- The username is the email address, and then type in the password for the email address.
- Once completed hit “Done” and try sending another email. The issue should be resolved.