You may learn more by capturing a few failed SMTP sessions with
tcpdump.
Wietse
Wietse,
You are correct, I learned more but not enough for me, at least, to
figure out what it means.
Clarification, thru all this I've talked about connecting to icloud.com
mx. For the purposes of this test I did a tcpdump for the subnet that
all the mx servers reside on. The PTR records return a different result
(xxx.me.com) but are the same servers.
There were several attempts from postfix to connect to 6 different mx
servers to deliver one email. They all have the same result so I'm only
including the dump of the first here:
reading from file postfix.cap, link-type EN10MB (Ethernet)
2014-05-03 22:29:50.755792 IP smtp.bestwny.com.36708 >
nk11p00mm-mx006.me.com.smtp: Flags [S], seq 3314275386, win 1400,
options [mss 1460,nop,wscale 6,sackOK,TS val 170874802 ecr 0], length 0
E..<.e@.@..........r.d.....:.......x...............
/W.....
2014-05-03 22:29:50.803327 IP nk11p00mm-mx006.me.com.smtp >
smtp.bestwny.com.36708: Flags [S.], seq 851616152, ack 3314275387, win
33304, options [nop,nop,TS val 803912023 ecr 170874802,mss
1460,nop,wscale 1,nop,nop,sackOK], length 0
E(.@$b@.2..p...r.......d2......;.....V.....
/..W
/W.............
2014-05-03 22:29:50.803385 IP smtp.bestwny.com.36708 >
nk11p00mm-mx006.me.com.smtp: Flags [.], ack 1, win 21, options
[nop,nop,TS val 170874848 ecr 803912023], length 0
E..4.o@.@..........r.d.....;2..............
/W./..W
2014-05-03 22:29:51.926871 IP nk11p00mm-mx006.me.com.smtp >
smtp.bestwny.com.36708: Flags [S.], seq 851616152, ack 3314275387, win
33304, options [nop,nop,TS val 803912136 ecr 170874802,mss
1460,nop,wscale 1,nop,nop,sackOK], length 0
E(.@$c@.2..o...r.......d2......;...........
/...
/W.............
2014-05-03 22:29:51.926896 IP smtp.bestwny.com.36708 >
nk11p00mm-mx006.me.com.smtp: Flags [.], ack 1, win 21, options
[nop,nop,TS val 170875972 ecr 803912136], length 0
E..4..@.@..........r.d.....;2..............
/\D/...
2014-05-03 22:29:54.195922 IP nk11p00mm-mx006.me.com.smtp >
smtp.bestwny.com.36708: Flags [S.], seq 851616152, ack 3314275387, win
33304, options [nop,nop,TS val 803912362 ecr 170874802,mss
1460,nop,wscale 1,nop,nop,sackOK], length 0
E(.@$d@.2..n...r.......d2......;...........
/...
/W.............
2014-05-03 22:29:54.195953 IP smtp.bestwny.com.36708 >
nk11p00mm-mx006.me.com.smtp: Flags [.], ack 1, win 21, options
[nop,nop,TS val 170878242 ecr 803912362], length 0
E..4..@.@..c.......r.d.....;2..............
/e"/...
2014-05-03 22:29:58.713053 IP nk11p00mm-mx006.me.com.smtp >
smtp.bestwny.com.36708: Flags [S.], seq 851616152, ack 3314275387, win
33304, options [nop,nop,TS val 803912814 ecr 170874802,mss
1460,nop,wscale 1,nop,nop,sackOK], length 0
E(.@$e@.2..m...r.......d2......;.....?.....
/..n
/W.............
2014-05-03 22:29:58.713079 IP smtp.bestwny.com.36708 >
nk11p00mm-mx006.me.com.smtp: Flags [.], ack 1, win 21, options
[nop,nop,TS val 170882759 ecr 803912814], length 0
E..4..@.@..........r.d.....;2..............
/v./..n
2014-05-03 22:30:07.717105 IP nk11p00mm-mx006.me.com.smtp >
smtp.bestwny.com.36708: Flags [S.], seq 851616152, ack 3314275387, win
33304, options [nop,nop,TS val 803913715 ecr 170874802,mss
1460,nop,wscale 1,nop,nop,sackOK], length 0
E(.@$f@.2..l...r.......d2......;...........
/...
/W.............
2014-05-03 22:30:07.717136 IP smtp.bestwny.com.36708 >
nk11p00mm-mx006.me.com.smtp: Flags [.], ack 1, win 21, options
[nop,nop,TS val 170891763 ecr 803913715], length 0
E..4!.@.@..........r.d.....;2..............
/../...
2014-05-03 22:30:25.735938 IP nk11p00mm-mx006.me.com.smtp >
smtp.bestwny.com.36708: Flags [R.], seq 1, ack 1, win 33304, length 0
E(.($g@.2......r.......d2......;P....Y..
2014-05-03 22:30:25.736215 IP smtp.bestwny.com.59558 > 17.158.8.71.smtp:
Flags [S], seq 3843436255, win 1400, options [mss 1460,nop,wscale
6,sackOK,TS val 170909782 ecr 0], length 0
E..<%g@.@..........G...............x...............
/.V....
As you can see, no 220 was returned to Postfix
I then did a capture of a telnet session to the same server on port 25:
reading from file telnet.cap, link-type EN10MB (Ethernet)
2014-05-03 22:35:14.821306 IP smtp.bestwny.com.58803 >
nk11p00-smtp-mx003.mac.com.smtp: Flags [S], seq 3396279601, win 65535,
options [mss 1460,nop,wscale 6,sackOK,TS val 171198862 ecr 0], length 0
E..<t.@.@.C........2.....o.1.......................
4I.....
2014-05-03 22:35:14.869697 IP nk11p00-smtp-mx003.mac.com.smtp >
smtp.bestwny.com.58803: Flags [S.], seq 1071218802, ack 3396279602, win
33304, options [nop,nop,TS val 406558553 ecr 171198862,mss
1460,nop,wscale 1,nop,nop,sackOK], length 0
E(.@`.@.2.em...2........?..r.o.2.....H.....
.;.Y
4I.............
2014-05-03 22:35:14.869751 IP smtp.bestwny.com.58803 >
nk11p00-smtp-mx003.mac.com.smtp: Flags [.], ack 1, win 1040, options
[nop,nop,TS val 171198912 ecr 406558553], length 0
E..4t.@.@.C........2.....o.2?..s...........
4I..;.Y
2014-05-03 22:35:14.931907 IP nk11p00-smtp-mx003.mac.com.smtp >
smtp.bestwny.com.58803: Flags [P.], seq 1:139, ack 1, win 33304, options
[nop,nop,TS val 406558560 ecr 171198912], length 138
E(..`.@.2.d....2........?..s.o.2.....'.....
.;.`
4I.220 nk11p00mm-smtpin017.mac.com -- Server ESMTP (Oracle
Communications Messaging Server 7u4-27.08(7.0.4.27.7) 64bit (built Aug
22 2013))
2014-05-03 22:35:15.025661 IP smtp.bestwny.com.58803 >
nk11p00-smtp-mx003.mac.com.smtp: Flags [.], ack 139, win 1040, options
[nop,nop,TS val 171199072 ecr 406558560], length 0
E..4t.@.@.C........2.....o.2?..............
4J`.;.`
2014-05-03 22:35:21.434234 IP smtp.bestwny.com.58803 >
nk11p00-smtp-mx003.mac.com.smtp: Flags [P.], seq 1:24, ack 139, win
1040, options [nop,nop,TS val 171205472 ecr 406558560], length 23
E..Kv`@.@.A........2.....o.2?..............
4c`.;.`EHLO smtp.bestwny.com
2014-05-03 22:35:21.482488 IP nk11p00-smtp-mx003.mac.com.smtp >
smtp.bestwny.com.58803: Flags [.], ack 24, win 33304, options
[nop,nop,TS val 406559215 ecr 171205472], length 0
E(.4`.@.2.ew...2........?....o.I...........
.;..
4c`
2014-05-03 22:35:21.483075 IP nk11p00-smtp-mx003.mac.com.smtp >
smtp.bestwny.com.58803: Flags [P.], seq 139:395, ack 24, win 33304,
options [nop,nop,TS val 406559215 ecr 171205472], length 256
E(.4`.@.2.dv...2........?....o.I.....>.....
.;..
4c`250-nk11p00mm-smtpin017.mac.com
250-8BITMIME
250-PIPELINING
250-CHUNKING
250-DSN
250-ENHANCEDSTATUSCODES
250-EXPN
250-HELP
250-XADR
250-XSTA
250-XCIR
250-XGEN
250-XLOOP 5FD8A7158C627CE6C2DD92D78FDB33EF
250-ETRN
250-NO-SOLICITING
250 SIZE 0
2014-05-03 22:35:21.575676 IP smtp.bestwny.com.58803 >
nk11p00-smtp-mx003.mac.com.smtp: Flags [.], ack 395, win 1040, options
[nop,nop,TS val 171205622 ecr 406559215], length 0
E..4vk@.@.A........2.....o.I?..............
4c..;..
2014-05-03 22:35:27.584480 IP smtp.bestwny.com.58803 >
nk11p00-smtp-mx003.mac.com.smtp: Flags [F.], seq 24, ack 395, win 1040,
options [nop,nop,TS val 171211622 ecr 406559215], length 0
E..4w.@.@.@Q.......2.....o.I?..............
4{f.;..
2014-05-03 22:35:27.632735 IP nk11p00-smtp-mx003.mac.com.smtp >
smtp.bestwny.com.58803: Flags [.], ack 25, win 33304, options
[nop,nop,TS val 406559830 ecr 171211622], length 0
E(.4`.@.2.eu...2........?....o.J...........
.;.V
4{f
2014-05-03 22:35:27.633216 IP nk11p00-smtp-mx003.mac.com.smtp >
smtp.bestwny.com.58803: Flags [F.], seq 395, ack 25, win 33304, options
[nop,nop,TS val 406559830 ecr 171211622], length 0
E(.4`.@.2.et...2........?....o.J...........
.;.V
4{f
2014-05-03 22:35:27.633248 IP smtp.bestwny.com.58803 >
nk11p00-smtp-mx003.mac.com.smtp: Flags [.], ack 396, win 1040, options
[nop,nop,TS val 171211672 ecr 406559830], length 0
E..4w.@.@.@J.......2.....o.J?..............
4{..;.V
I am clueless as to why telnet would receive a correct response but
Postfix not.
I know see this is not necessarily a Postfix issue but not sure what the
next step would be, so if anyone can offer guidance it would be
appreciated.
