Thanks for reaching out. An address that consistently bounces as non-existent is placed on an internal hold and labeled as "Suspended" to prevent us from sending to it again. We do this because repeatedly sending email to the same non-existent address can negatively impact deliverability. Thus, we recommend that you would remove this address from your contacts. In the event the Suspended address is in fact valid, there is additional troubleshooting you can do.
Also, you can access the Help Center by clicking the icon in the top right corner of your account:
The online Help Center provides access to frequently asked questions, video tutorials, webinars, and much more!