Emails are sent with “on behalf”

Hi!

I’m using the plugin in my website, and I have found a minor problem.

All emails that are sent by my WordPress site are showing up in Android Outlook App with “on behalf” text in the header.
Messages “from” line has following text:
“john.doe@myemail.com on behalf of John Doe”
Of course I’m not using those addresses 🙂

Outlook Webapp, that is opened in browser is not showing the “on behalf” text. Also Gmail is not showing any “on behalf” texts.

I have configured the “Envelope-From Email Address” and the “Email Address” in the Post SMTP settings to be the same email address, so I’m not sending the emails as “on behalf”.

Whether I’m sending my emails with plugin I usually use for it (MailPoet), or if I’m trying Post SMTP’s “Send test mail” function, the problem is the same.

I’m thinking it might be because of the “sender” address doesn’t have name in it, but “From” address does.
This is how I see it in the email source:
Sender: <john.doe@myemail.com>
From: John Doe <john.doe@myemail.com>

That makes sens to me, but is there any way to fix this?
I don’t like that my recipients are getting confused with that weird phrase.

Sincerely,
Olli