Most email clients allow entering a sender address for other to use when replying to your email. This address can usually be
whatever you enter, independent of the SMTP server you use for outgoing email. (There is, of course, no use in entering an invalid email address or an address not controlled by you, though it is possible). If you read email for your domain name by
forwarding, you may enter the email address of your own domain name as the sender address instead of the real address.