Hi, I´m writing to you because between 7th and 8th January I had the following problem with the SMTP server:

The mail server is running Qmail with tcpserver and daemontools, and during the days I have just mentioned it generated an excess of connections of the program rblsmtpd. This happened because whenever the program made a query to bl.spamcop.net the connection stayed in "close_wait" state, and the consequence was about 92 or 115 connections in "close_wait" state. This caused the server to stop accepting more SMTP connections and it didn´t allow the clients to connect to the server and send mail.

As the primary mail server didn´t accept more connections, these connections were sent to the secondary mail server, which finally was saturated -since we have near 1300 clients-. I restarted the server, but the connections rblsmtpd in "close_wait" state increased immediately, and the server returned to the previous behavior -not accepting more SMTP connections-.

Finally I realized that the solution to the problem was "killing" the rblsmtpd connections that were in "close_wait" state and then the clients were able to connect again to the server without having any problem. Therefore, the only idea I could think of was creating a scri_pt that verified the rblsmtpd connections in "close_wait" state every 5 minutes and "killed" them.

I had been working with spamcop for blocking the spam on the server since long time ago, and nothing like this had ever happened to me. That´s why I would like to know if the last days you had had any kind of problem and, if not, I would be grateful if you could please suggest me a better solution to this problem than what I thought of.

I also need to know how much time the rblsmtpd takes for making a query and if every time it makes a query the connection is closed immediately (this is the way it works?)

I really thank you for your help, since it´s fairly important for me to solve this problem.


P.D.: my concurrency incoming of SMTP connections is set to 70 at the moment.

Hi!
...Sorry I can not answer your question (I am not an e-mail server admin but some other members are, so you may get an answer from one of them) but I just wanted to acknowledge your inquiry.
...Good luck!

turetzsr, thank you for your feedback. It's good to know that some members will be able to answer my questions.