We have been using a form of email authentication referred to as Sender ID for for quite some time. This form of authentication results in much higher levels of deliverability, as it is a standard form of authentication.
For certain email clients, including some versions of Outlook, when an email is authenticated, subscribers may be notified of this authentication.
After they open the email, in the "From" line where the sender's address appears, they may see something that looks like the following:
From: firstname.lastname@example.org on behalf of email@example.com
Does This Appear to Every Subscriber?
This special message will only appear to a minority of subscribers using only a select number email applications, including certain versions of Outlook.
Certain email clients may not say "on behalf of," rather they may say something such as "via send.aweber.com." Here is an example of how this would look in Gmail:
Why Is It Needed?
Email authentication is important for the deliverability of your messages. When your messages are authenticated, ISP's will be able to determine that you are sending from a genuine server. This can help with preventing your message from hitting SPAM filters that you may normally hit when sending from your own personal email address.
Note: In certain cases you may be able to prevent that "on behalf of" from appearing in your messages by updating your SPF records. While this may not work in all scenarios, it is something that you can certainly still try.