Charlie chiseled,
| Besides, one could assume that those subscribed to a digested mailing list | would _expect_ irregular deliveries as part of the package - multiple issues | per day when things are hopping, none some days when things aren't.
I have found that sometimes digest-mode subscribers get antsy; maybe not after twenty-four hours but certainly after seventy-two. Was there an issue that failed to reach them, or which a person with whom they share the email address (with so many free webmail and popmail servers and five screen names per AOL account one would think that nobody need share an address any more, but people still do) see it first and delete it? After all, some of them choose digest mode specifically because issues are numbered and they can be sure whether they're getting them all. (There also are mailing list packages that number the articles.) They will ask, and you can always instruct them to check the archives if there is a digest-mode archive.
If the archives carry only individual messages, one thing I found that worked was a mailback command to the -request address that returns the volume num- ber, issue number, and timestamp of the most recent digest, plus the number of articles since then that are queued for the next issue.