The Debugging Level Checking the Mail Queue

rewrite: ruleset 0 returns: ether apollo . ph . myschool . scps . edu : bjl apollo . ph . myschool . scps . edu 0 bjlacf4.yourschool.edu rewrite: ruleset 3 input: bjl acf4 . yourschool . edu rewrite: ruleset 6 input: bjl acf4 . yourschool . edu rewrite: ruleset 6 returns: bjl acf4 . yourschool . edu rewrite: ruleset 3 returns: bjl acf4 . yourschool . edu rewrite: ruleset 0 input: bjl acf4 . yourschool . edu rewrite: ruleset 9 input: bjl acf4 . yourschool . edu rewrite: ruleset 9 returns: bjl acf4 . yourschool . edu rewrite: ruleset 0 returns: ddn mail1 . scps . edu : bjl acf4 . yourschool . edu D The same test procedure can be implemented for other rulesets and addresses.

20.4.3 The Debugging Level

The level of information that sendmail displays during the testing can be arbitrary selected; the sendmail command with the −d option is used for this purpose: sendmail −d level where level corresponds to the selected debugging level. Numbers identify the debugging levels. Larger numbers correspond to higher debugging levels with more detailed displayed information. Selecting a higher debugging level does not always make it easier to determine the source of an error. The displayed data could contain too much useless information, while the important piece becomes hidden between all of the unimportant data. Once selected, a debugging level remains active until the next new level higher or lower is selected again.

20.4.4 Checking the Mail Queue

sendmail is also a very powerful tool for checking the mail queue. As we know, all unprocessed e−mail requests are temporarily stored in the mail queue for later processing. sendmail periodically reprocesses the mail queue for a certain period the default is 5 days before it returns an error message to the sender about undelivered e−mail; the queued e−mail is then removed from the queue. The command sendmail −bp displays the status of the mail queue. It is recommended that you run this command occasionally to check for possible problems in mail queuing. Too many pending e−mail requests are usually a sign of some sendmail −related problems. Too many queued e−mail requests could keep sendmail daemons so busy that e−mail starts to work improperly. The mail queue is located in the varspoolmqueue directory by simply listing the directory and counting the listed files: ls varspoolmqueue | wc −l 491 The command sendamil −qv is very instrumental in forcing e−mail queue processing the q option, and provides a verbose display of all steps in the processing the v option. A great deal of information about pending e−mail requests can be obtained by combining these two commands, and this may help point out eventual problems in the sendmail configuration.

20.5 Mail User Agents