Exchange 2013 send connector after provider switch started sending on behalf of.
We have a on premises exchange 2013 server.
we receive through a pop3 into the server via 3rd party software which is working fine.
then when we send out we have a send connector with the providers smtp details ( say email@example.com as send account)
our previous provider we sent email from firstname.lastname@example.org through the send connector and it was received by recipient from the sender "email@example.com"
we changed our provider - all settings are the same in the smtp bar the new password but now the email is received as from "firstname.lastname@example.org on behalf of email@example.com"
I have no idea why the change of smtp provider would cause this as surely this is controlled in Exchange
any help much appreciated