Can only send mail to some addresses

Hi,

I have a problem when sending mail from wordpress.

My admin email is set as alias1@domain.com, which is an alias to mainuser@domain.com (a g suite email).

I have set up WP Mail SMTP via OAuth to use g suite as mailer.

If i send a testmail to either alias1@domain.com or mainuser@domain.com it works.

But now I want to change my admin email to wordpress@domain.com, and the confirmation mail never arrives, same for all other aliases, that are not the one that is set as admin email address.

Please help.