How to find the top domains currently being processed by your postfix mail queue.

If you want to get a glimpse of what's grinding away in your postfix MTA's mail queue, this simple bash one liner will give you the top 15 domains that it's working with:

$ mailq | grep ^[A-Z\|0-9] | awk '{print $7}' | cut -d@ -f2 | sort | uniq -c | sort -rn  | head -15

To break it down, we're first getting a queue list by running the mailq command. Then we pipe that to grep and filter for only those lines that begin (^) with a capital letter [A-Z or (\|) a number 0-9], which gives all lines that begin with a Queue-ID.

If we look at one of those lines, we see that the 7th field contains the email address of the sender and that's what we grab using the awk statement. Then we split the email address on the @ symbol and just grab the second field which is the domain (cut -d@ -f2).

Then we sort those results and pipe them to the uniq utility which we use to count the references. With those counts in place, we do a reverse sort on the counts (sort -rn) in order to give us the busiest domains first and then use the head statement to just give us the top 15.

When it's all done, you get something like this as output:

   1274 example100.com
     89 example2.com
     85 example3.org
     83 example5.net
     68 example8.info
     64 example10.org
     57 example7.com
     55 example15.com
     50 example1.net
     50 example20.com
     45 example45.com
     41 example60.net
     40 example33.com
     38 example6.com
     38 example34.com

This post has been edited by Jim-J: 02 February 2010 - 07:10 AM