Strange smtp problem
- From: "Jack" <pac-edge@xxxxxxxxx>
- Date: 7 Oct 2006 01:04:52 -0700
Hello all, hope someone can help or point me in the right direction.
Client with docsis cable modem Internet access - upgraded from regular
cable 2 weeks ago - this involved cable modem change, isp head-end
equipment change (docsis), ip address change, and reverse dns pointer
change (isp). There were some complaints about missing email approx. 1
month ago but these were not taken too seriously due to difficulty in
proving they were sent (IE from outside) - now I'm starting to wonder
......
SBS 2000 sp4, not 100% certain of exchange update status.
The problem began several days ago when a sister company (physically
only blocks away) (same isp, same head-end isp router) could not send
emails to said client recipients. Some emails do get through although
sporadic. The ones that do not get through vanish into the ether - no
ndr, no nothing. The other end is Exchange 2003 Standard (sp2) on 2003
Server Standard (sp1).
I have used telnet to troubleshoot (details below). This morning I had
an isp rep come to the other site. The first 20 times I tried
telnetting in I got the 220 header every time, by the time he left
(after I had gone to two other sites via vpn and tried with varying
success, the problem was back with a vengeance - zero 220 banners in 20
tries - frustrating and confusing.
The test is just telnet ipaddress 25 - the ADLS sites came up with the
220 banner each time, although several iterations were delayed by 2 to
4 seconds before the banner appeared. When the test 'failed' I mean
the cursor went to top left corner or one to right of that and stayed
there until I hit any char which would cause it to drop out.
2 nights ago I spent 2.5 hrs doing the telnet test from 5 different
sites, using 20 reps each, then doing a tracert and documenting the
results. That made me think that it was a router issue because it did
not fail from two sites that were on ADSL. When I checked the tracert
output it was clear that a specific isp router that worked for the ADSL
sites was not being traversed when I checked the other 'external' sites
(IE different isp) which also 'failed' my testing. Tonight I ran
network monitor each end whilst doing the telnet test - I see the
banner going out from the target machine but not coming in to telnet
side machine, so it's getting lost somewhere between the target
Sonicwall on out - have not yet set up detail logging on Sonicwall -
maybe tomorrow.
I am not too sure what I am dealing with here (isp, cable modem,
sonicwall, exchange, o/s, or ??), should also mention that the two
sites in close proximity are Sonicwall soho3 unlimited units. All the
others are varying Sonicwall models.
Also saw MS KB 895857 - will try that tomorrow but doesn't seem to fit
that well.
Any help would be much appreciated -
.
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