Over ten years ago, I asked on this list how I could get rid of the "incorrect pipelining message" logged by postfix every time the smtp, smtps, or submission tests are done. https://lists.xymon.com/oldarchive/2010/11/msg00207.html The fix that I claim worked (multiple send commands) was for a job I had at the time. Now I am have a personal mail server (that also runs xymon) and that fix I mentioned so long ago is not working. I tweaked the code to allow a "pause" action in protocols.cfg and after modifying protocols.cfg to utilize it, I have eliminated the "incorrect command pipelining" message in mail.log. Here's the patch: --- xymon-4.3.28/lib/netservices.c 2017-01-05 19:00:06.000000000 -0700 +++ pause-xymon-4.3.28/lib/netservices.c 2021-05-29 12:51:09.717461323 -0600 @@ -259,6 +259,10 @@ } } } + else if (strncmp(l, "pause ", 6) == 0) { + int pausetime = atoi(skipwhitespace(l+5)); + sleep(pausetime); + } } if (fd) stackfclose(fd); Here's the new definitions I created in protocols.cfg: [smtp] pause 2 send "ehlo xymonnet.localdomain\r\n" pause 2 send "mail\r\n" pause 2 send "quit\r\n" expect "220" options banner port 25 [smtps] pause 2 send "ehlo xymonnet.localdomain\r\n" pause 2 send "mail\r\n" pause 2 send "quit\r\n" expect "220" options ssl,banner # No default port-number assignment for smtps - nonstandard according to IANA [submission|msa] pause 2 send "ehlo xymonnet.localdomain\r\n" pause 2 send "mail\r\n" pause 2 send "quit\r\n" expect "220" options banner port 587 And this is now what I see in mail.log (testing smtps and submission: May 29 13:51:15 bilbo postfix/submission/smtpd[16324]: connect from bilbo.elyograg.org[172.31.8.104] May 29 13:51:15 bilbo postfix/submission/smtpd[16324]: disconnect from bilbo.elyograg.org[172.31.8.104] quit=1 commands=1 May 29 13:51:15 bilbo postfix/smtps/smtpd[16325]: connect from bilbo.elyograg.org[172.31.8.104] May 29 13:51:15 bilbo postfix/smtps/smtpd[16325]: disconnect from bilbo.elyograg.org[172.31.8.104] quit=1 commands=1 Interesting thing here is that it's not actually pausing. Which probably means that I implemented it incorrectly. My training on C is ancient and I'm very rusty. But even though it doesn't pause, the error is gone, simply because each smtp command is now sent in a separate packet, which appears to *sometimes* be enough "delay" for postfix to not complain about pipelining. What happens now is occasionally I will get a yellow status on smtps with the xymon UI saying "Service smtps on bilbo.elyograg.org is not OK : Unexpected service response". So I think what I will do before submitting a patch is implement a "null" action (which will do nothing) as well as a "pause" action, and get some help from the real C developers here for making "pause" behave as advertised. Can somebody point me to some instructions on properly creating and submitting a patch? Also, if I could get some info on any other files I need to modify (man pages, readme files, etc), I would really appreciate it. Thanks, Shawn