We use Sender ID for email authentication. This results in much higher levels of deliverability, as this is a standard form of authentication. For certain email clients, including versions of Outlook, when an email is authenticated, subscribers are notified of this authentication through the way the email FROM address is written.
After you open the email, in the "From" line where the sender's address appears, you would see the following:
From: firstname.lastname@example.org on behalf of email@example.com.
OR in some cases (like gmail):
From: firstname.lastname@example.org via butterflypublisher.com
This Will Not Appear for Everyone
This message will only appear to some subscribers using only a select number email applications, including certain versions of Outlook. Email clients like gmail may use 'via' instead.
Why Is It Needed?
Email authentication is important for the deliverability of your messages. When email is authenticated, ISP's will be able to determine that you are sending from a genuine server. This can help avoid your message hitting SPAM filters that you may normally hit when sending from your own personal email address.