Please note that this is not the same as How to use Gmail's "Send Mail As" with another Gmail account through SMTP without "On Behalf Of"? which is to do with removing the message for send as aliases.
If I delegate access to my Gmail account to somebody else, they are able to access my account and send emails on my behalf. Unfortunately, when the recipient views the message, it will have "on behalf of" and then that person's email address appended.
Is there any way to prevent this from happening?
Ironically, if that person were to setup a send as alias in their personal account with my address, the on behalf of message does not appear.
Best Answer
No, there isn't.
Instead the delegated account could be added to the delegate mailbox as another email address or alias.
References
Send mail from a different address or alias - Gmail Help