Removing 'on behalf of' when sending mail using MailGun

Question

I\'m trying to figure out how to send mails using the MailGun Golang API without having it sent \'on behalf of\'.

This is how the From address currently looks (where f

Answer 1

To add to Dhodgin's answer:

The on behalf of message comes up if you're using a subdomain in MailGun such as mail.bar.com and the from email address is using a different domain such as john@foo.com
To fix this issue add a custom MIME header "sender" and set it to be the same as the from email address.

To add a custom header using the MailGun api make sure to add a h: prefix such as:

request.AddParameter("h:sender", "John Smith  ");