email address improperly flagged as invalid

[Tue, 30 Mar 2021 19:18:12 UTC, FreeToastHost System Warning]

Emails sent to the primary email address [ hbarton@sfwmd.gov ] for Member Hope Barton, DTM in Club 5173 have bounced too many times and exceeded the FreeToastHost limit for bounces.

This automatically generated message is to notify you that this email address ***has been removed*** from the FreeToastHost database to prevent it from causing further bounces. If you are able to resolve the issue with the email address, you will need to re-enter it in the system.
I can assure you hbarton@sfwmd.gov is a valid and active email address. This is one of many sfwmd.gov email addresses in members-5173@toastmastersclubs.org. Only hbarton seems to be getting singled out as invalid. What's going on?


Repeatedly attempting to send emails to invalid, non-working email addresses hurts the overall email reputation of the FreeToastHost system and will not be tolerated.

Please ensure that valid, functioning email addresses are in use to prevent further actions of this nature in the future.

If you have any questions about this warning, please visit support.toastmastersclubs.org and provide us with this message

We are not currently blocking or bouncing email to hbarton@sfwmd.gov

I sent a test email to hbarton@sfwmd.gov and is shows being accepted by her email processor.
Please have her add server@toastmastersclubs.org and server@toastmastersclubs.org to her safe/contacts list

Apr 5 12:51:50 toastmastersclubs sendmail[2250]: 135CpmxX002247: to=<hbarton@sfwmd.gov>, ctladdr= (501/502), delay=00:00:02, xdelay=00:00:02, mailer=esmtp, pri=121210, relay=sfwmd-gov.mail.protection.outlook.com. [104.47.65.110], dsn=2.0.0, stat=Sent (<202104051251.135CpmxX002247@toastmastersclubs.org> [InternalId=25477746012961, Hostname=BLAPR09MB7266.namprd09.prod.outlook.com] 10253 bytes in 0.074, 134.372 KB/sec Queued mail for delivery)