[Mailman-Users] mail delivery failed

[Remy .RIGO. N.]

Hello,
I need help please. I am the administrator of a mailing list on Mailman 2.1.9 . It's been 3-4 days, mails are not being delivered. Not mine, or anyone else from the list. They are not held for approval by the admin, and no message or error is being sent. The emails just disappear once I hit SEND.
I checked all the options of the mailing list, to which I am the only one who has access, and found nothing that could prevent the messages from going through in or out.

Can anyone help? I know very little about computers and codes, so please be patient and baby-talk lol
~ Rémy .RIGO. Nassar ~