With so many solutions, how can you tell which solutions are most likely to help you and which ones are not? To provide you with a tool to use, we rate our solutions based on various elements that most accurately determine if a solution is a quality solution. To explain what factors affect the solution rating, here are the elements we take into consideration when formulating our solution rating.
The Grade of the Solution
The Zone Rank of the Expert Providing the Solution
The Number of Author and Expert Comments
The Number of Experts Contributing
The Feedback of the Community
Your Input Matters Because of the way the system is set up, the most important variable in this equation is you. As a member of Experts Exchange, you are able to cast your vote on the quality of the solutions in regard to how complete, accurate, helpful and easy to understand each solution is. When you provide your feedback, each rating is adjusted accordingly. So, if you see a solution that has a poor rating that you think is a good solution, let us know by rating it. As you do, the rating will be adjusted and will become more accurate for other members of our site.
If you have any suggestions that you would like to make for our rating system, please ask a question in the Suggestions Zone of Community Support.
Hello! I have a problem with a debian etch sendmail mailserver. -> Debian Etch, no hacks, Sendmail 8.13.8/8.13.8/Debian-3) Sendmail stops (or very slow) responding on port 25 when there are many connections. (Problems occur when there are around 300-400 simultaneous connections on port 25) There is no error in the mail logs, its not a throtteling or load problem, no max_children limit. Checked all sendmail settings. Sendmail is still responding with other daemon on port 587 (and fast!). Checked ulimit and port settings on linux box (kernel 2.6.21.5), enough free space on hdd.
Maybe another limit? Maybe i missed something! I hate all these spammers causing the problems! (> 90% off all emails are spam or being rejected!)
- Port 25 and 587 are handled by the same daemon process - "strace -p DAEMON_PID -t -e trace=network" shows an incoming connection from an test ip on port 587 but not on port 25
So i think it is not a sendmail problem, but a connection problem. A limit on concurent connectios to a single incoming port? never had such a problem. The server has > 300 (problems begin) concurrent connection on port 25 and a total of > 1000 tcp connections
Actually, the TCP/25 and TCP/587 daemons are probably completely separate processes. TCP/25 is the MTA, TCP/587 is the MSA.
If you don't have any connection limits configured in sendmail, then yeah, someone could be running your host out of resources. Each connection takes up a finite amount of RAM and CPU. Perhaps you should turn on some connection rate limits.
Check out my profile for some links to technical papers on this sort of thing. In particular, read "Practical Modern sendmail Configuration"
Hello! Meanwhile i found a solution. Now i do DNS based load balancing on the server: The incoming connections on port 25 are splitted on 5 different IP-Adresses on the one server. Everything is working fine now. For every IP i have a sendmail daemon listening. Up to now, this is my solution. Regards
