Why can some emails display as “on behalf of” or “via”?
Regardless of your ‘From’ address settings which you choose for each message, it may happen that some of your subscribers see:
From: firstname.lastname@example.org on behalf of
The situation described above may occur for only some of your subscribers using certain email clients and email applications like Gmail and Outlook. Unfortunately, this setting is determined by the email client and is not something that GetResponse can control.