• The length of time since the last mailing.
• The accumulative size of the messages not yet sent.

You can adjust both variables by changing the options.

Every time a message is posted to the list, the program evaluates if either threshold has been met.

If your list is not very active, you will want to keep both settings low. Smaller settings will minimize delays in releasing the digest format. Your list could have messages accumulated for a pending digest (neither criteria has been met yet); those messages will remain pending until a new message comes in to trigger another evaluation or until the time setting has been reached.

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Taglines: Turning Commerical Taglines On/Off