1. Log into your MyGuestlist account

2. Click on 'Sent Items' in the GREEN menu

3. In the table at the top of the screen, to the right of 'Emails unread', select 'Add Unread Emails to Category'

The name of the category will be the name of your campaign with [unread] in front of it.

So for example if I use 'Feb Newsletter' as my campaign name, the category name will be:

[unread] - Feb Newsletter

Now that you have all of those patrons in a category, you can re-send your campaign to them. 

See here for Re-Sending a Campaign.