Problem with Email Mailing List

Greetings Everyone!

I am having problems with our email mailing list which I use to distribute the agenda to our club members each week. The errors occurred on the 25th May 2026, twice in rapid succession, and I have been too scared to try sending out another email since then.

Soon after sending the first email with the agenda, I received an automated message telling me that there had been an error and the email could not be sent. I quickly tried sending out a second email with the agenda, however soon afterwards multiple copies of the same email began arriving in everyone's inboxes. It was like the website thought the email had not gone through, and so was continually attempting to resend it, even though it was clearly reaching the club membership.

I have attached screenshots of the error messages. I believe screenshot 3 shows the error message I received shortly before all the duplicate emails started appearing. I believe screenshots 1&2 show the error messages I received shortly after the duplicate emails finally ceased.

Any advice would be appreciated. If any further information is needed just let me know.

This is all for Charlestown Toastmasters located in Australia. Club Number is 6345. This email were sent via the Thunderbird Email Client.