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Unreachable mail server

glocal
Grafter
Posts: 88
Thanks: 2
Registered: 11-09-2007

Unreachable mail server

My IMAP connection to mail.hud.ac.uk suddenly stopped working about a week ago.
Traceroute shows:
 
Tracing route to mail.hud.ac.uk [161.112.232.30]
over a maximum of 30 hops:
  1    15 ms    99 ms    99 ms  dsldevice.lan [192.168.1.254]
  2    35 ms    35 ms    36 ms  lo0-central3.thn-ag1.plus.net [195.166.128.228]
  3    36 ms    35 ms    36 ms  gi1-5-131.thn-gw1.plus.net [84.92.6.112]
  4    35 ms    39 ms    36 ms  po6.ptn-gw01.plus.net [212.159.1.137]
  5    35 ms    35 ms    35 ms  po4.ptn-gw02.plus.net [212.159.1.139]
  6    36 ms    35 ms    35 ms  linx-gw2.ja.net [195.66.226.15]
  7    36 ms    35 ms    35 ms  ae1.lond-sbr3.ja.net [146.97.35.173]
  8    37 ms    37 ms    37 ms  as0.read-sbr1.ja.net [146.97.33.165]
  9    41 ms    41 ms    41 ms  as3.warr-sbr1.ja.net [146.97.33.90]
10    42 ms    43 ms    42 ms  YHMAN-L2.site.ja.net [146.97.42.130]
11    43 ms    43 ms    43 ms  v495.hdd-d01.yhman.net.uk [194.81.1.203]
12    43 ms    43 ms    43 ms  161.112.232.30
13    43 ms    *        *    161.112.232.30
14    *        *        *    Request timed out.
15    *        *        *    Request timed out.
16    *        *        *    Request timed out.
17    *        *        *    Request timed out.
18    *        *        *    Request timed out.
19    *        *        *    Request timed out.
20    *        *        *    Request timed out.
21    *        *        *    Request timed out.
22    *        *        *    Request timed out.
23    *        *        *    Request timed out.
24    *        *        *    Request timed out.
25    *        *        *    Request timed out.
26    *        *        *    Request timed out.
27    *        *        *    Request timed out.
28    *        *        *    Request timed out.
29    *        *        *    Request timed out.
30    *        *        *    Request timed out.
Trace complete.

And ping shows:
 
Pinging mail.hud.ac.uk [161.112.232.30] with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Ping statistics for 161.112.232.30:
    Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

However, both traceroute and ping from a third party (eg http://network-tools.com) work fine and other users of that mailserver don't seem to have a problem. Any ideas?
2 REPLIES
mxs
Grafter
Posts: 70
Registered: 08-12-2010

Re: Unreachable mail server

I can ping the host but getting duplicate responses returned - could be a network misconfiguration on their side (it could just be a mistake that affects a subset of addresses hence working fine for some).

PING mail.hud.ac.uk (161.112.232.30) 56(84) bytes of data.
64 bytes from 161.112.232.30: icmp_req=1 ttl=116 time=17.1 ms
64 bytes from 161.112.232.30: icmp_req=1 ttl=116 time=17.2 ms (DUP!)
64 bytes from 161.112.232.30: icmp_req=2 ttl=116 time=16.3 ms
64 bytes from 161.112.232.30: icmp_req=2 ttl=116 time=16.3 ms (DUP!)
64 bytes from 161.112.232.30: icmp_req=3 ttl=116 time=15.9 ms
64 bytes from 161.112.232.30: icmp_req=3 ttl=116 time=16.0 ms (DUP!)
64 bytes from 161.112.232.30: icmp_req=4 ttl=116 time=15.7 ms
64 bytes from 161.112.232.30: icmp_req=4 ttl=116 time=15.9 ms (DUP!)
64 bytes from 161.112.232.30: icmp_req=5 ttl=116 time=15.7 ms
--- mail.hud.ac.uk ping statistics ---
5 packets transmitted, 5 received, +4 duplicates, 0% packet loss, time 35132ms
rtt min/avg/max/mdev = 15.758/16.305/17.253/0.547 ms, pipe 2

Traceroute stops a hop before yours before it reaches the server:
traceroute to mail.hud.ac.uk (161.112.232.30), 30 hops max, 60 byte packets
1  192.168.1.254 (192.168.1.254)  0.303 ms  0.504 ms  0.529 ms
2  lo0-central2.pcl-ag06.plus.net (195.166.130.47)  21.889 ms  21.936 ms  21.982 ms
3  gi7-9-621.pcl-gw01.plus.net (84.93.254.137)  221.564 ms  221.622 ms  221.818 ms
4  po5.ptn-gw01.plus.net (212.159.1.131)  21.987 ms  22.958 ms  23.017 ms
5  po4.ptn-gw02.plus.net (212.159.1.139)  42.231 ms  42.439 ms  42.484 ms
6  linx-gw2.ja.net (195.66.226.15)  27.351 ms  25.119 ms  25.122 ms
7  ae1.lond-sbr3.ja.net (146.97.35.173)  21.614 ms  21.650 ms  21.679 ms
8  as0.read-sbr1.ja.net (146.97.33.165)  21.753 ms  21.806 ms  25.089 ms
9  as3.warr-sbr1.ja.net (146.97.33.90)  32.860 ms  32.916 ms  34.767 ms
10  YHMAN-L2.site.ja.net (146.97.42.130)  34.867 ms  34.926 ms  34.962 ms
11  v495.hdd-d01.yhman.net.uk (194.81.1.203)  39.904 ms  44.770 ms  23.659 ms
12  * * *
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Community Veteran
Posts: 14,469
Registered: 30-07-2007

Re: Unreachable mail server

This problem is outside the Plusnet network so there is nothing they can do to help. You need to contact the company responsible for the mail server.