Marketo Email Invalid vs. Email Suspended Fields

I see a lot of Adobe Marketo users still at times getting tripped over the Email Suspended and Email Invalid fields - which field gets updated when, and what are the nuances around each?

Email Suspended and Email Invalid fields are system fields that are updated to True when Marketo receives a failed delivery notification back from the recipient's MX server due to a hard bounce. These fields also have their reason/cause fields (Email Suspended Cause and Email Invalid Cause), which store the reason for the failed delivery as returned by the recipient's MX server.

The Email Suspended field is set for category 1 hard bounces, i.e., when the recipient's MX server bounced the email citing it as spam or blacklisting it, whereas the Email Invalid field is set for category 2 hard bounces, i.e., when the email address is invalid or simply doesn't exist, thereby implying a bad email address.

Furthermore, unlike the Email Invalid and Email Invalid Cause fields, which could be updated by the end-user or by campaign flows, the Email Suspended and Email Suspended Cause fields are strictly system-managed fields and hence cannot be updated by the end-user or by campaign flows.

Lastly, “Email Suspended” places a temporary block on the person's availability for 24 hours, unlike the Email Invalid field. The Email Suspended field itself doesn’t get reverted to False after 24 hours, but the suspension lasts only for 24 hours. You should check the “Email Suspended” timestamp. If it’s more than 24 hours ago, the lead is not currently suspended and can receive email from your Marketo instance.

I hope this post will help clear up some clouds/refresh everyone's knowledge.