Hello @kathyp521 ,
Please do not post contacts' sensitive data in our public forum.
A contact becomes suspended in our system when you or other customers of ours have tried to send to them in the past, and they've bounced back from the domain / IP as non-existent. Make sure to check out our main article on suspended bounces for additional insight.
If you've unsuspended the contacts from within your account, as a follow-up I'd recommend doing a Quicksend of the last email they were supposed to receive. If we receive a report from their domain / ISP about them being 'non-existent' again, then they'll likely be put back into suspension. You can check this by going to the contact's engagement history right after doing the Quicksend. If the non-existent bounce occurs again, then it'd be best to reach out to our Deliverability team to see if they have any additional insight regarding that domain / ISP. Otherwise the contacts will simply not be viable to send to through our system.
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