Why do recipients sometimes see “via” or “On Behalf Of” as part of the FROM address in their email program?

ContentMX Email Deliverability, Knowledge Base

This information appears because we are providing the email authentication needed for the deliverability and security of your email campaigns.

How authentication works

By default, it is fairly easy to forge your identity when sending email. All you do is set the FROM address and name to whatever name you would like. For instance, anyone can pretend to be a bank or credit card company. Authentication techniques help prevent this from happening. An authenticated email clearly indicates who is sending an email and which mail servers have the authority to send it. Email servers can check the authenticity of an email, and if it fails the check the email can be blocked or marked as spam.

The most common types of email authentication are DKIM (Domain Keys Identified Mail) and SPF (Sender Policy Framework). Services like AOL, Gmail and Yahoo and many corporate mail servers use one or more of these authentication methods to verify sender identity.

ContentMX makes the process of authenticating email simple because we authenticate all of your email for you. This is why the “via butterflypublisher.com” may appear as part of the from address. The email is being sent on your behalf by us, and butterflypublisher.com is the authorized sender.