The toggle in question is SET listname DIGEST SET listname NODIGEST The "SET listname MAIL" and "SET listname NOMAIL" commands simply determine whether or not mail (either a digest, index, or individual postings) is sent. If a DIGEST mode user sets NOMAIL while on vacation, then comes back and sets MAIL, he resumes getting the digest, not individual postings. This has been the behaviour since the release of 1.8b. Here's the quote from the 1.8b list owner's release notes (which should more or less be what is in the list owner's and general user's manuals today): ******************************************************* * Usability: Change in MAIL, DIGEST and INDEX options * ******************************************************* Originally, the MAIL, DIGEST, INDEX and NOMAIL options corresponded to the four possible settings of a single option. That is, switching from DIGEST to NOMAIL would stop the delivery of new digests, as expected, but would also make LISTSERV forget that the subscription should be in digest mode. A subsequent switch to MAIL would restore delivery, but in normal (non-digest) mode. This was confusing to novice users. In version 1.8b, the MAIL/NOMAIL option has been isolated from DIGEST/INDEX. The MAIL/NOMAIL option controls whether messages should be delivered, and the DIGEST/INDEX/NODIGEST/NOINDEX option controls the format in which messages should be delivered. Thus, switching to NOMAIL and back to MAIL now preserves the digest/index/normal delivery setting. To provide as much compatibility with the old syntax as possible, the four options now operate as follows: - DIGEST: enable digest delivery mode (which negates INDEX), enable mail delivery. No change from version 1.8a. - INDEX: enable index delivery mode (which negates DIGEST), enable mail delivery. No change from version 1.8a. - NOMAIL: disable mail delivery. No change from version 1.8a. - MAIL: restore mail delivery, without altering the digest/index/normal delivery setting (new behaviour). For compatibility with 1.8a, if mail delivery was already active, the MAIL option negates INDEX/DIGEST. Thus, a user going from NOMAIL to MAIL will keep his previous delivery options, whereas a user going from DIGEST or INDEX to MAIL will in fact deactivate index/digest mode. To revert from digest/index subscription mode to normal delivery, you can use either the MAIL option as before, or the NODIGEST/NOINDEX option. The NODIGEST and NOINDEX options were actually present in versions 1.7f and 1.8a, as synonyms for the MAIL option. In other words, you can update your instructions to indicate that the DIGEST/INDEX options are negated by the NODIGEST/NOINDEX options, even if your server is not yet running version 1.8b.