How to bring up a snowballing open rate
When your open rate is low it can be due 1) Poor engagement, 2) Unmonitored inboxes, or 3) Disinteresting subject lines.
In my experience as a HubSpot email consultant number one is by far the most prevalent. People often ask, how can a low open rate be caused by poor engagement aka. a low open rate?
The issue starts if you become known to have a low open rate by ISP's like Gmail and/or Outlook (who provide 62% of all inboxes out there). Once you get this reputation they will start filterring your emails to the spam folder. This obviously causes an even lower open rate, and the issue starts to snowball.
The only way to break out of this cycle is to increase overall open rate by suppressing the contacts who will not open moving forward. How do you know which contacts won't open in the future. Well, unless your Emailstradamus you don't know 100%. However, the best way to take an educated guess is to make a list of the contacts you are currently sending to that haven't ever opened an email from you. Chances are overwhelming that those contacts will continue to not open email.
You can create a HubSpot list of these contacts using the Last marketing email opened date and Marketing emails delivered properties:
Last marketing email opened date is unknown
"But what about the brand new contacts? They haven't had a chance to open yet. I don't want to suppress them." To fix our list for this segment we will want to use a HubSpot default property called Marketing emails delivered. This property increments by one for each email a contact is delivered:
Marketing emails delivered > X
OK so now we have the list. What do we do with it? Well the most important thing is to stop sending email to these people. They are dragging down your overall open rate. Suppressing this list mitigates the risk that your future email will go to the spam folder.
Option 2 - If you would like to try one more email before giving up on these folks, then you may be inspired by one of these 9 slick re-engagament campaigns. Otherwise just let them go. 
