Well, this I just experienced a few minutes ago, and I think I should blog it. After queuing a mail on 127.0.0.1 smtp server in evening, I found that it was still not delivered. On tailing /var/log/maillog I found that smtp port of smtp.gmail.com is unreachable. I tried to telnet smtp.gmail.com on smtps port, there I got connected. So, I thought Gmail might have dropped support for relaying mails via smtp port, only smtps port. So then I asked one of my friend Edwin, who is fortunately online from non-Indian (or to be more precise, non-Airtel) network, to connect to smtp port of smtp.gmail.com. He told me that he is able to connect. Now, the next thought that came in my mind, Gmail has blocked smtp port of a specific box (though chances of that is very low, as these companies are running cluster of servers for load balancing, and anyways I never worked on clustered network :( ). So I tried another IPv4 address of smtp.gmail.com, still same problem. Then I thought to try connecting to another SMTP server’s smtp, so this time I tried MX of microsoft.com, still same problem, so then I checked my box’s and my ADSL modem’s iptables, but no such rule found. So then I called Gautam to know if he is already experiencing this problem. So he also confirmed me the same. Then Edwin suggested me that I should try tcptraceroute to see where packets were being dropped. Following is the stuff which I did:
[wahjava@chatteau ~]$ sudo tcptraceroute smtp.gmail.com -p 25
Password:
traceroute to smtp.gmail.com (72.14.215.109), 30 hops max, 40 byte packets
1 172.16.0.1 (172.16.0.1) 1.503 ms 2.419 ms 3.376 ms
2 rasBTNLDel-static-135.215.56.202.mantraonline.com (202.56.215.135) 366.339 ms 367.289 ms 368.254 ms
3 rasBTNLDel-static-230.215.56.202.mantraonline.com (202.56.215.230) 378.217 ms 380.183 ms 384.148 ms
4 * * *
5 * * *
6 * * *
7 * * *
8 rasBTNLDel-static-162.215.56.202.mantraonline.com (202.56.215.162) 3340.447 ms !X * *
[wahjava@chatteau ~]$ sudo tcptraceroute smtp.gmail.com -p 995
traceroute to smtp.gmail.com (209.85.133.111), 30 hops max, 40 byte packets
1 172.16.0.1 (172.16.0.1) 1.479 ms 2.408 ms 3.352 ms
2 rasBTNLDel-static-135.215.56.202.mantraonline.com (202.56.215.135) 20.312 ms 22.271 ms 23.240 ms
3 rasBTNLDel-static-230.215.56.202.mantraonline.com (202.56.215.230) 33.203 ms 34.168 ms 36.131 ms
4 rasBTNLDel-static-162.215.56.202.mantraonline.com (202.56.215.162) 48.099 ms 50.066 ms 51.032 ms
5 203.101.95.181 (203.101.95.181) 52.985 ms 53.949 ms 60.921 ms
6 203.101.100.29 (203.101.100.29) 84.881 ms 61.776 ms 65.554 ms
7 203.101.100.237 (203.101.100.237) 99.229 ms 101.843 ms 107.750 ms
8 202.56.223.29 (202.56.223.29) 103.664 ms 108.346 ms 3062.296 ms
9 203.208.147.45 (203.208.147.45) 3303.216 ms 303.740 ms 298.521 ms
10 203.208.149.57 (203.208.149.57) 321.219 ms 296.750 ms 297.529 ms
11 * * *
12 209.85.130.6 (209.85.130.6) 337.195 ms 295.753 ms 296.539 ms
13 66.249.95.212 (66.249.95.212) 362.315 ms 352.741 ms 354.526 ms
14 72.14.238.155 (72.14.238.155) 375.188 ms 72.14.239.19 (72.14.239.19) 378.140 ms 386.085 ms
15 216.239.43.13 (216.239.43.13) 379.977 ms 216.239.49.22 (216.239.49.22) 401.926 ms 402.796 ms
16 209.85.133.111 (209.85.133.111) 1969.214 ms 1969.046 ms 1969.025 ms
[wahjava@chatteau ~]$ sudo tcptraceroute smtp.ncr.airtelbroadband.in -p 25
traceroute to smtp.ncr.airtelbroadband.in (202.56.230.30), 30 hops max, 40 byte packets
1 172.16.0.1 (172.16.0.1) 1.593 ms 2.507 ms 3.457 ms
2 rasBTNLDel-static-135.215.56.202.mantraonline.com (202.56.215.135) 398.424 ms 399.378 ms 403.343 ms
3 rasBTNLDel-static-230.215.56.202.mantraonline.com (202.56.215.230) 404.307 ms 406.274 ms 408.237 ms
4 rasBTNLDel-static-162.215.56.202.mantraonline.com (202.56.215.162) 414.203 ms 416.167 ms 435.135 ms
5 203.101.95.181 (203.101.95.181) 433.101 ms 434.066 ms 439.032 ms
6 * * *
7 smtp.airtelbroadband.in (202.56.230.30) 5374.574 ms 5374.184 ms 5374.113 ms
[wahjava@chatteau ~]$ dig +short smtp.ncr.airtelbroadband.in
202.56.230.27
202.56.230.30
[wahjava@chatteau ~]$ telnet smtp.ncr.airtelbroadband.in smtp
Trying 202.56.230.27...
Connected to smtp.ncr.airtelbroadband.in (202.56.230.27).
Escape character is '^]'.
220 ****************************************************************
^]
telnet> quit
Connection closed.
[wahjava@chatteau ~]$ sudo tcptraceroute smtp.ncr.airtelbroadband.in -p 25
Password:
traceroute to smtp.ncr.airtelbroadband.in (202.56.230.27), 30 hops max, 40 byte packets
1 172.16.0.1 (172.16.0.1) 1.434 ms 2.346 ms 3.297 ms
2 rasBTNLDel-static-135.215.56.202.mantraonline.com (202.56.215.135) 263.255 ms 268.210 ms 271.172 ms
3 rasBTNLDel-static-230.215.56.202.mantraonline.com (202.56.215.230) 270.139 ms 274.102 ms 276.069 ms
4 rasBTNLDel-static-162.215.56.202.mantraonline.com (202.56.215.162) 280.034 ms 280.991 ms 285.953 ms
5 203.101.95.181 (203.101.95.181) 287.920 ms 288.886 ms 290.852 ms
6 203.101.100.198 (203.101.100.198) 291.817 ms 321.753 ms 322.518 ms
7 smtpout.airtelbroadband.in (202.56.230.27) 973.533 ms 973.181 ms 973.111 ms
As clear from the above dump, that outgoing TCP packets to smtp port are dropped at 202.56.215.162, but 202.56.215.162 allows packets to smtp.ncr.airtelbroadband.in. So, what do you conclude from this ? Anyways, I reported this to their customer care, but customer care representative told me that they’re currently having some problem with some 3rd party websites. And he told me that issue will be resolved tomorrow. Let’s hope it get resolved soon.