A few of our emails got suspended due to the mail sever accidentally finding them as SPAM and we need hep to un-suspend them. I had heard that after 24 hours they will automatically get un-suspended however this was not the case.
Right now it is over 30 hours and yet nothing.
I am also unable to manually un-suspend them.
Any help would be appreciated.
Don't worry, they will get unsuspended in our system but that field in Marketo will not get changed back automatically. The name of the field should probably be "Email was suspended at some point"
You could create a campaign to set it back to false for people that haven't had it changed in last 24 hrs. But, totally unnecessary. Only if you are a perfectionist.
Have you tried creating a batch campaign that runs nightly to un-mark the email suspended addresses? You could also export them, delete them from the instance, then re-import them and then that would reset their suspended status.
If you look at the detail in the suspend message here https://kb.mimecast.com/Email_Gateway_and_Security/Email_Gateway_Administration/Monitoring/Mimecast_... you will see that 5XX codes are considered almost universally considered hard/permanent bounces.
In my experience with many other systems your example would be considered a hard bounce.