We use HubSpot to send newsletters. Some of our customers have ‘previously hard bounced’ due to reasons such as their mailboxes being full at the time.
Those same customers are contacting us saying that they no longer receive newsletters, and would like to, but I am unsure how to override the contact bouncing.
I cannot send an opt-in email as the customers have already opted-in.
I have asked for written consent to confirm that they want to receive our newsletters containing marketing information.
What can I do, please? Any guidance would be appreciated.