Use the If Viewed Specific Email condition to follow up with contacts, based on whether they: 

• Did view a selected email;
• Or Did not view a selected email.

"Did view" example use

Send a follow up email campaign to contacts who have shown interest by viewing your “Investment Opportunities” email, with an invite to an upcoming Investment seminar. *

After setting your recipients, as well as your schedule:

• Add a new module and choose the condition of If Viewed Specific Email.
  • Within the module, set the condition to Did view.
  • From the dropdown options, select the email you want to follow up on, e.g.: "Investment Opportunities".
• Add a new module and choose Send Email.
  • Within the module, select your follow up email, e.g.: "Investment Seminar"
• Once all your selections are made, select Save, or Save & Activate.

* You could also use the Viewed Email trigger.

"Did not view" example use

Send an email campaign to contacts who did not recently open and view your "Must read" email, to prompt them to take notice of an important announcement. *

After setting your recipients, as well as your schedule:

• Add a new module and choose the condition of If Viewed Specific Email.
  • Within the module, set the condition to Did not view.
  • From the dropdown options, select the email you want to follow up on, e.g.: "We've Moved!".
• Add a new module and choose Send Email.
  • Within the module, select your follow up email, e.g.: "New address reminder"
• Once all your selections are made, select Save, or Save & Activate.