Email continues to get put on the bounce list

I have a clients whose email continuously gets put on the bounce list. I remove it and then two day later it is back on there. This has been an issue for over a month. I need to get this resolved ASAP

If an address is continually being placed on our bounce list, the issue is likely with filtering on their end.  When emails are blocked as spam, it raises our spam score and increases the probability of further emails being blocked.  To prevent this, we place addresses on our bounce list that block emails.

To prevent this from happening, you can send emails from your own address via SMTP:

https://www.jotform.com/help/244-How-to-Setup-SMTP-for-a-Form

Or switch to another service such as Gmail that does not have such strict filtering policies.