UpdateFrequency is the minimum amount of time in minutes that is allowed to pass between WikiNewsletter mailings. For instance, if this value is set to 60, and changes are made to the wiki every five minutes, you will still receive only one email every hour, with all the changes for that hour. If there are no changes, no email is sent.

Note further that if the minimum amount of time has passed, mail will be sent immediately. For example, imagine the UpdateFrequency is set to 60 (one hour). Further imagine that it is 3PM and no changes have been made since 1PM. If someone then makes two changes at 3PM and at 3:05PM, two emails will be sent: the first email will be triggered at 3PM when the wiki engine notices that a change has been made and no newletter has been sent within an hour. The second email will be sent at 4PM, because although the wiki engine will notice at 3:05PM that another change occurred, it will hold off sending a newsletter until at least an hour has passed since the last newsletter was sent.