[MM3-users] Mailing list resends same email multiple times

Hello, I need your help. There have question about Scenes:

 Add mailbox a and mailbox b to mailing lists c and mailing lists d, and send mail to mailing list c and mailing list d through mailbox b , among which a has received many mails sent by b, check the log and find: The file about path:/opt/mailman /var/queue/bounces has the content of retrying mail, but I turned off process bounces.

Mailing list sends mail via exim, logs found in exim： 023-03-09 00:54:47 1pa4YR-001xk5-0y <= <> R=1pa4YM-001xje-1F U=exim P=local S=7672 T="Mail delivery failed: returning message to sender" from <>

Thanks

TomNewChao