Two Emails Receiving Bounce Backs

The emails in our club for aharbor@austin.utexas.edu and jrc@austin.utexas.edu are bouncing back.

The message I get when I email them from our club website is, "skipped because it has previously bounced too many times. Please visit support.toastmastersclubs.org and post a support request message for more information."

Attached are two pictures of this too.

Question 1: Is there a way to get this reset for them?
Question 2: Is there any way to prevent this from happening in the future?


(For Club 1555969 at utstaff.toastmastersclubs.org/ )

The Bounce Count for Email Address [aharbor@austin.utexas.edu] has been reset to zero.
The Bounce Count for Email Address [jrc@austin.utexas.edu] has been reset to zero.

the errors are below, I hope they have been fixed

Your email message to aharbor@austin.utexas.edu could not be delivered
and was returned to the FreeToastHost server. Details are as follows:

Recipient Email Address: aharbor@austin.utexas.edu
Email Subject: [FreeToastHost] Message Not Delivered: UT Staff Toastmasters Club
Date Sent: Mon, 30 Mar 2020 16:28:19 +0000

Diagnostic Code: 550 5.7.1 Connection from 50.19.253.65 rejected, see
Delivery Status: 5.1.1 userunknown
Date Last Attempted: Mon, 30 Mar 2020 16:28:20 GMT

Your email message to jrc@austin.utexas.edu could not be delivered
and was returned to the FreeToastHost server. Details are as follows:

Recipient Email Address: jrc@austin.utexas.edu
Email Subject: [FreeToastHost] Message Not Delivered: April 3: Agenda for TM
Date Sent: Mon, 30 Mar 2020 17:30:25 +0000

Diagnostic Code: 550 5.7.1 Connection from 50.19.253.65 rejected, see
Delivery Status: 5.1.1 userunknown
Date Last Attempted: Mon, 30 Mar 2020 17:30:26 GMT