This morning I received the following message:
"Your subscription has been disabled on the [email protected] mailing list because it has received a number of bounces indicating that there may be a problem delivering messages to"
After some investigation I found that the IPv6 address of the amsat mail server is blacklisted by spamhaus, there mail from this address is rejected.
https://www.spamhaus.org/css/removal/record/2600:3c02::f03c:92ff:fe92:3fc7
To the mail administrators please investigate and send a request to spamhaus for list removal.
Jan PE0SAT