Uwe Ohse


automated SMTP server survey


These surveys shall measure which SMTP server software is in real use now.


A reliable source of addresses of mail servers in active use are the logfiles of the ISP i work for: Only the hosts we succesfully delivered email to are queried later.


Once a day a script walks through the logfiles and takes the IP addresses of mailservers we delivered email through. These addresses are compared to a database to make sure i query them only once a month.
Another script connects to the every host and sends the following commands:
EHLO csl18.csl-gmbh.net
HELO csl18.csl-gmbh.net
(only in case EHLO was not accepted)

The output is recorded and later analysed by another script. This script is the weak part of the system: It's far to horrible now. IP-address of the server, type (or unknown), version (if recognized) and date are put into a database.

Once a month a list is generated and included here.


Unfortunately the numbers are slightly biased:
  1. we usually install qmail on our servers and often on customers machines.
  2. a coworker likes MDaemon on NT.

The numbers

This service has been discontinued due to time constraints and trouble with some server admins, resulting in DoS attacks on my machine.