Digest Keyword

Digest= No
Digest= Yes,where | Same[,frequency][,when][,Size(maxsize)][,BOTTOM_BANNER]

This keyword controls the automatic digestification function, allowing subscribers who do not have the time to read large numbers of messages as they arrive to subscribe to a digestified or indexed version of the list. The list owner decides whether digests are available or not, the frequency at which they are issued, and the day of week or time of day when the digest should be distributed.

Digests are larger messages containing all the postings made by list subscribers over a certain period of time. LISTSERV digests are not edited; what you see is exactly what was posted to the list. The only difference is that you get all the messages for a given day, week or month in a single batch. Digests are kept separately from list archives and can be made available for mailing lists that do not archive postings (that is, those which run with "Notebook= No").

Indexes, on the other hand, only provide a few lines of information for each posting: date and time, number of lines, name and address of poster, subject. The actual text is not included. You select just the messages you are interested in, and access them from the server. This is useful for mailing lists where most messages don't interest you, or as an alternative to NOMAIL. Note that since indexes are not useful without the ability to access a copy of the messages you want to read, they are not made available unless list archives and digests are enabled.

Users sign up for digestified rather than immediate delivery with 'SET listname DIGests', while indexes are selected with 'SET listname INDex'. These two options are alternatives to MAIL and NOMAIL. When switching around between these delivery options, users will observe the following behavior (digests will be assumed to be daily for the sake of clarity):

• When switching to NOMAIL, the delivery stops immediately. The day's digest is not sent, as the user is assumed to desire immediate termination of traffic from the list. Any mail already "in the pipeline" to the subscriber will still be delivered.
• When switching from any option to DIGEST or INDEX, the mail delivery stops immediately, and the first index or digest may contain some items the user has already seen (if switching from MAIL to DIGEST/INDEX). This is because the digests and indexes are global to the list – they are the same for everyone, just like regular issues of newspapers.
• When switching from DIGEST or INDEX to NODIGEST or NOINDEX, the current, unfinished digest or index is immediately mailed to the user. New messages are delivered normally as they arrive. Thus, a "trick" to get a copy of the current digest is to switch to NODIGEST and then back to DIGEST.

The list owner controls the availability and frequency of digests through the "Digest=" list header keyword, which defaults to "Digest= No" for lists without an archive and "Digest= Yes,Same,Daily" for archived lists. Again, it is not necessary for the list to be archived to keep a digest; LISTSERV just attempts to avoid having to store large amounts of digest data on its private area for lists which, lacking a "Notebook= Yes,xxx" keyword, do not specify any suitable directory for the digest data. Conversely, having "Daily" as the default frequency keeps the additional cost in disk space to a minimum.

The syntax of the keyword is "Digest= Yes,where,frequency,when,maxsize" when digests are enabled. The second parameter is a disk or directory specification, just as with the "Notebook=" keyword, or "Same", which means that the digest must be stored on the same disk as the list archives.

The third parameter is either "Daily" (the default), "Weekly", or "Monthly".

The fourth parameter is optional and specifies when the digest is to be actually distributed. For daily digests, specify 'hh:mm' or just 'hh' in the usual 00-23 scale (24 is also accepted for midnight). Note that daily digests are cut on the hour, regardless of whether or not you have provided ":mm" in your setting. For weekly digests, specify a weekday such as "Tuesday". For monthly digests, you may specify a number from 1 to 31 corresponding to the day of the month when the digest will be distributed, although this is not recommended. The purpose here is to make it possible for digests to be issued at mid-month rather than on the first of the month. If you code a number larger than 28, you may not get a digest every month.

The fifth parameter is also optional. It takes the form "Size(number)" and specifies the maximum number of lines the digest is allowed to reach before a "special issue" is cut. Note that your digests may run over the limit set in "Size(number)". This is because LISTSERV will never truncate a message in order to meet the digest size limit. Thus, if you've reached 950 lines of your 1000 line setting and the next message is 100 lines long, your digest will cut at 1050 lines. The default is 10,000 lines.

The list owner must take special care when disabling digests for a list, as LISTSERV does not presently have any facility that would allow it to alter subscription options automatically on the basis of changes to the list header. Subscribers who had opted for digests would continue not to receive mail as it arrives, but would not get the digests either. The best way to solve this problem is to announce the change long enough in advance, so that people can switch back before digests are suspended. The reason nothing has been done to remove this limitation is that it is not expected to be a frequent condition. Daily digests take up very little disk space and there is no reason to disable them for a typical list.

Specify the BOTTOM_BANNER parameter to force a copy of the banner to be printed at the top of the digest in the table of contents.

Note that BOTTOM_BANNERs and TOP_BANNERs are always included in each message in the digest, regardless of whether you specify the BOTTOM_BANNER parameter.

The second parameter of the "Digest=" keyword ("where") may only be changed by the LISTSERV administrator. A list owner is allowed to change "Digest= No" to "Digest= Yes,Same....", but any other specification for the digest file location will cause an error. A list owner is also allowed to change "Digest= Yes..." to "Digest= No" without the intervention of the LISTSERV administrator. Note that if the list is not archived ("Notebook= No"), changing "Digest= No" to "Digest= Yes,Same" will cause the digest files to be written to the LISTSERV A disk (or equivalent specification on workstation systems). Since the overhead for a typical digest is small, it is not expected that this will cause any problem for the LISTSERV administrator.