In my opinion there really is no need to keep them around. We use unsubscribe to manage all of the privacy and compliance regulations. If we don't have evidence of the lead opting-in, then we unsub them and set an unsub reason. We leave them unsubscribed until we have verification of opt-in. This protects our marketers from emailing opt-outs. If the lead record is deleted at the leads request or during a cleanup job, the durable unsubscribe provides us the protection of emailing them.  I have a set of programs that reviews the unsubscribes and those older than 9 months with no activity are deleted..   If the contact returns, through a form fill or a list import, one of our processing steps enriches the lead record so we get a fresh set of data and don't stress about keeping them around in Marketo or in an external file.   You just need to determine how much prior activity is enough to keep the lead around although we haven't found anyone that unsubscribed with a lot of activity.   Hope that helps, Dennis ... View more

Thank you for the tip.  It was a result of the SSL certificates not being enabled. I contacted support to enabled, waited, and it seemed to clear up. And I added the versioning string to my templates, and it has helped already. Thanks again. ... View more