Anti-Spam: Why Set Your List to Send=Public,Confirm or Send=Private,Confirm

By adding the Confirm option, the sender will be required to confirm their message before it is posted to the list.  This reduces the problem of spammers posting to your list by faking the return address.

What difference will your users experience?

When someone sends an email message to your list, LISTSERV will respond to the sender with the following message:

For  security reasons,  the ITS-LISTSERV  list has  been configured  to request positive confirmation of messages posted to the list. You must now confirm that the enclosed  message did  originate from you.  To do so,  simply reply  to the present message and type "OK" (without the quotes) in the text of your message, or click on  the link below. If this  does not work, or if the  message did not originate from you, then contact the list owner for assistance.


To APPROVE the message:

The sender must either reply to the message with OK (as described above) or click on the link provided in the email.

If they choose to click on the link, LISTSERV will return:

LISTSERV Command Response message

Anti-Spam: Tips to Decrease Spam to the List

Send Keyword Settings:

  • Send = Private,Confirm <- Recommended default setting for non-moderated lists.
    Only members of the list can send to the list.
  • Send =Public,Confirm

    Anyone can send to the list.

  • Send = Public,Confirm,Non-Member
    These options allow anyone to post to the list, but if the sender address is not subscribed to the list, the sender must confirm their message before it is posted to the list. List members do not need to confirm their messages.
  • Send=Owner,Confirm
    Only the list owners can send to the list.
    Only the email addresses listed can send to the list.
  • Send = Editor,Hold,Confirm,All
    All messages must be approved by the editor (moderator) before being posted to the list.
  • Send = Service,Confirm
    Service = *,*


    Setting the above Send and Service keywords will limit the allowed senders to addresses.
    Setting Filter=also,* disallows messages sent with the fake email return addresses of other LISTSERV lists.
    Details about the service keyword are available at:

Additional Keyword Settings:

  • Confidential = Yes <- Recommended default setting for lists.
    Setting the Confidential command to Yes, removes the name of the list from the public list-of-lists.
  • Subscription = xxxxxxxx,Confirm
    The Confirm option requires the sender to confirm their subscription.
  • Moderated or Announce-Only lists. You also set your list as moderated or announce-only.
  • More tips can be found at Tech Tip (LISTSERV) - Issue 3 - 2007 by L-Soft.

Anti-Spam: Tips to Decrease Spam to the List Owner

  • LISTSERV 15.5 provides the following enhancement: All messages sent to the LISTSERV-REQUEST, ALL-REQUEST or listname-REQUEST addresses will require confirmation from the sender before they will be passed on to the appropriate person(s).

There is not a confirmation for messages sent to the OWNER-listname address.  That is a special administrative address used by LISTSERV to interact with list owners. By default all messages sent to OWNER-listname go to the list owner. We recommend you filter these messages based on the message subjects: Undelivered mail and error report. See How to Filter Email Messages.

  • For edited lists, set Send = Editor,Hold,Confirm,All
    This setting will require that all senders confirm that they actually sent the message before it is forwarded to you, the editor.
  • If you are tired of receiving the message below, we suggest you set a filter to remove them from your inbox. See How to Filter Email Messages.

    The enclosed message, found in the listname mailbox and shown under

    the spool ID 26241576 in the system log, has been identified as a

    possible delivery error notice for the following reason: "Sender:",

    "From:" or "Reply-To: "field pointing to the list has been found in mail body."

Article number: 
Last updated: 
March 22, 2019