Cannot re-subscribe bounced emails

Hi, please can someone assist us? We are a paying customer and have submitted a support ticket, but have not heard anything for over three days.

Our company email provider experienced a problem last Friday, and our mails were bouncing for a period of about 8 hours. Unfortunately, this included a Mailpoet newsletter with most of our company staff addresses, which also bounced and the addresses were moved to the bounced list in Mailpoet. The mail problem has been resolved for several days now, but I cannot successfully re-subscribe these addresses. Whenever I try to do this, nothing is sent to the addresses and Mailpoet then moves them back to the bounced list again. All our other incoming mail is fine. How do I get these addresses re-subscribed?

Simon