How can I decipher qmail's logs?

Reading the qmail log files is not a trivial excercise. Many mail administrators use applications such as:

1. qmailanalog

2. Sean Truman has some mrtg scripts.

3. Bruce Guenter wrote qlogtools

4. Monte Mitzelfelt has a program which sorts a qmail log file by message delivery.

5. Ismail Yenigul has a qmail log analyzer tool called IsoQlog.

There are a further list of applications on the qmail.org home page.

If you want some quick and dirty results for a quick query you could use a combination of custom script to perform the following actions:

1. Search the logs for "info msg N: bytes M from SENDER" entries.

2. Note the message ID, N.

3. Search forward for "starting delivery K: msg N to remote/local RECIPIENT" entries.

4. For each one you find before the first "end msg N" entry, you've discovered a recipient.