Apparently, when you create an account nowadays on Gmail, and add another custom domain (e.g. @marks.dk), it doesn’t add the message “xxx@gmail.com sent on behalf of xxx@marks.dk” as it used to.
I just tested it with a couple of email addresses, in the following way:
1. Create a new Gmail-account
2. Go to Settings > Accounts and Import
3. Click “Send mail from another address”
4. Enter the email-address you want to send form (e.g. test@marks.dk)
5. Choose “Send through Gmail”
6. Click “Send Verification”
7. Gmail sends an email to the email-address you want to send on behalf of. Click the link.
8. Now you can send emails from gmail.com through a custom email-address with your own domain.
This behavior is new, but I really appreciate the change. A quick search will reveal lots of arguments from Google on why they had to add the text for security measures etc., but it’s changed now. Yay.