smtp.plus.net not responding

[#1]

The stock Mail app on my iPhone has stopped connecting to the mail server (smtp.plus.net).  If I use an app to ping or traceroute it they both fail.  I've tried various online ping and traceroute utilities, one of which does multiple traceroutes from different start points, and they all fail somewhere in BTs network.   PN service status reports no issue.  What gives?

[#2]

5 hours later, still no joy.

Traceroute to smtp.plus.net (212.159.9.107), 64 hops max.
1 50.187-105-213.static.virginmediabusiness.co.uk (213.105.187.50) time=20 ms
2 popl-lam-5-tenge41-1266.network.virginmedia.net (62.252.29.149) time=15 ms
3 popl-core-2b-ae11-0.network.virginmedia.net (82.14.168.13) time=19 ms
4 *
5 eislou2-ic-2-ae0-0.network.virginmedia.net (62.254.84.62) time=33 ms
6 linx4.ukcore.bt.net (195.66.236.11) time=12 ms
7 core2-hu0-16-0-1.southbank.ukcore.bt.net (109.159.252.243) time=21 ms
8 *
9 195.166.129.176 (195.166.129.176) time=21 ms
10 84.93.224.48.plus.net (84.93.224.48) time=33 ms
11 *
12 *
13 *
14 *
15 *
16 *
17 *
18 *
19 *
20 *
21 *

[#3]

I've just tested this on my own e-mail address in the format of mailbox@username.plus.com and I've been able to send an email from it and that's been successfully received, although I've been using relay.plus.net as the outgoing server.

Can you try changing the SMTP server to that? Let us know how you get on.

[edit]

Also are you able to try sending mail from a different connection than the one you're currently on?

[#4]

I’m set up to use smtp.plus.net for receive and relay.plus.net for sending but they both resolve to the same IP address. If the IP address can’t even be pinged then it means it is unreachable. I have tried apps on 2 separate devices, on one of them (my phone) connected to WiFi and then 4G, and at least 5 different web based ping/traceroute utilities and none of them succeed. In each case a different start point will be used. Very odd, maybe some disruption in the internet world which means that some start points succeed and some don’t.

What do you get if you use https://traceroute-online.com/ - I get this:


Hop Host / IP Address ISP Country Packet Loss Response
1 207.99.1.13
router1-nac.linode.com. Linode, LLC
AS8001 - 207.99.0.0/17 0% 0.8 ms
2 173.255.239.10
- Linode, LLC
AS63949 - 173.255.239.0/24 0% 11.2 ms
3 66.198.111.165
ix-ae-13-0.tcore4.njy-newark.as6453.net. TATA COMMUNICATIONS (AMERICA) INC
AS6453 - 66.198.96.0/19 0% 1.0 ms
4 63.243.186.5
if-ae-11-14.tcore2.nto-new-york.as6453.net. TATA COMMUNICATIONS (AMERICA) INC
AS6453 - 63.243.128.0/17 0% 80.5 ms
5 80.231.20.106
if-ae-32-3.tcore2.ldn-london.as6453.net. TATA COMMUNICATIONS (AMERICA) INC
AS6453 - 80.231.0.0/16 0% 77.5 ms
6 80.231.20.2
- TATA COMMUNICATIONS (AMERICA) INC
AS6453 - 80.231.0.0/16 0% 81.1 ms
7 166.49.129.39
166-49-129-39.eu.bt.net. British Telecommunications plc
AS5400 - 166.49.128.0/17 0% 77.4 ms
8 109.159.252.171
core2-hu0-15-0-1.colindale.ukcore.bt.net. British Telecommunications PLC
AS2856 - 109.144.0.0/12 0% 77.3 ms
9 no response
- -
- ??? 0 ms
10 195.166.129.160
- British Telecommunications PLC
AS6871 - 195.166.128.0/19 0% 79.5 ms
11 84.93.232.61
84.93.232.61.plus.net. British Telecommunications PLC
AS6871 - 84.92.0.0/15 20% 88.7 ms
12 no response
- -
-

Bed time, maybe it will have sorted itself out by the morning.

[#5]

An SMTP server is for sending, something's definitely not right if you're trying to receive mail using smtp.plus.net. The incoming mail server needs to be mail.plus.net (POP3) or imap.plus.net (IMAP). Can you double check the outgoing server in your devices is definitely set to relay.plus.net and the incoming as one of the above?

[#6]

Sorry, my mistake - I am set up to use imap.plus.net for receive and relay.plus.net for send. However this is nothing to do with my email client, the problem is that the IP addresses are unreachable - it’s a network problem . This is what I get if I traceroute imap.plus.net whilst connected to the local WiFi (Virgin is the provider where I am currently):

Traceroute to imap.plus.net (217.46.26.38), 64 hops max.
1 50.187-105-213.static.virginmediabusiness.co.uk (213.105.187.50) time=7 ms
2 popl-lam-5-tenge41-1266.network.virginmedia.net (62.252.29.149) time=5 ms
3 popl-core-2b-ae11-0.network.virginmedia.net (82.14.168.13) time=8 ms
4 *
5 *
6 *
7 core1-hu0-7-0-3.southbank.ukcore.bt.net (194.72.16.149) time=365 ms
8 195.99.125.139 (195.99.125.139) time=55 ms
9 ge0-1-0-22.ptn-gw2.plus.net (195.166.129.210) time=30 ms
10 *
11 *
12 *
13 *
14 *
15 *
16 *
17 *
18 *
19 *
20 *
21 *
22 *
23 *
24 *
25 *
26 *

[#7]

If I do the same thing with community.plus.net it succeeds:

Traceroute to community.plus.net (143.204.195.26), 64 hops max.
1 50.187-105-213.static.virginmediabusiness.co.uk (213.105.187.50) time=48 ms
2 popl-lam-5-tenge41-1266.network.virginmedia.net (62.252.29.149) time=30 ms
3 popl-core-2a-ae11-0.network.virginmedia.net (82.14.168.9) time=32 ms
4 *
5 telw-ic-3-ae4-0.network.virginmedia.net (212.250.14.110) time=28 ms
6 52.95.218.120 (52.95.218.120) time=20 ms
7 54.239.101.30 (54.239.101.30) time=20 ms
8 150.222.65.3 (150.222.65.3) time=41 ms
9 *
10 *
11 *
12 54.239.44.204 (54.239.44.204) time=26 ms
13 54.239.100.76 (54.239.100.76) time=6 ms
14 52.94.35.135 (52.94.35.135) time=40 ms
15 *
16 *
17 *
18 *
19 *
20 server-143-204-195-26.lhr3.r.cloudfront.net (143.204.195.26) time=17 ms
*** Traceroute at destination ***

[#8]

This doesn't seem like a widespread problem, because I've been able to send mail fine. As you're not on a Plusnet connection, are your devices are set up to authenticate via your username and password when sending mail? 

[#9]

IP addresses need to be reachable before you get as far as authentication. traceroute and ping both show they are not, from multiple locations - or is there something special about those addresses that don’t allow traceroute or ping to get through to them? If that is the case then I am barking up the wrong tree. It would be good to know if anyone else can ping/traceroute imap.plus.net and/or relay.plus.net.

As you say it doesn’t look like a widespread problem otherwise you would be inundated. I will be home tomorrow and able to try from my Plusnet (autocorrect changed that to Pilsner!) Broadband and also from my laptop.

The mail client on my phone says ‘The mail server “imap.plus.net” is not responding’. It worked fine until a day or so ago and nothing has changed.

It’s not a disaster as I can use Webmail.

[#10]

I've never pinged or traced our email servers so I'm not sure what a trace should look like normally for this. As you're unable to send or receive mail, I'd suspect this may be IP address related with the internet connection you're on.

Let us know how it goes once you're home. In the meantime, hopefully there's someone who sees this thread and can shed some more light on this.

[#11]

I also get no response to pings or traceroute from my Plusnet IP (31.125.x.y) to the Plusnet SMTP and IMAP servers. However SMTP and IMAP work fine for me - I can send/receive Plusnet email on my phone & laptop okay.

I've not had to ping them before, so I wouldnt know if they've always been like this, or its a recent change.

Its not uncommon for some hosts/routers to be set to ignore pings or traceroute packets. A bit annoying for simple troubleshooting like this though. All that matters is its reachable on the port its providing service for.

For example "microsoft.com" does not reply to pings, but does respond to HTTP requests on TCP port 80:

$ ping -c 10 microsoft.com
PING microsoft.com (104.215.148.63) 56(84) bytes of data.
--- microsoft.com ping statistics ---
10 packets transmitted, 0 received, 100% packet loss, time 319ms

$ telnet microsoft.com 80
Trying 104.215.148.63...
Connected to microsoft.com.
Escape character is '^]'.
wibble
HTTP/1.1 400 Bad Request
Connection: close
Date: Sat, 08 Feb 2020 16:51:02 GMT
Server: Kestrel
Content-Length: 0

Connection closed by foreign host.

Similarly I get no response to pings for relay.plus.net or imap.plus.net and traceroute doesn't finish, but both are reachable on their respective service ports

$ ping -c 10 relay.plus.net
PING relay.plus.net (212.159.9.107) 56(84) bytes of data.
--- relay.plus.net ping statistics ---
10 packets transmitted, 0 received, 100% packet loss, time 226ms

but talks on port 587 (and also 25 and 465 not shown below)

$ telnet relay.plus.net 587
Trying 212.159.8.107...
Connected to relay.plus.net.
Escape character is '^]'.
220 avasout06 smtp relay.plus.net
quit
221 avasout06 smtp closing connection
Connection closed by foreign host.

Same for IMAP, doesnt ping:

$ ping -c 10 imap.plus.net
PING imap.plus.net (217.46.26.48) 56(84) bytes of data.
--- imap.plus.net ping statistics ---
10 packets transmitted, 0 received, 100% packet loss, time 365ms

but does respond on port 143 (and 993 not shown below)

$ telnet imap.plus.net 143
Trying 217.46.26.38...
Connected to imap.plus.net.
Escape character is '^]'.
* OK [CAPABILITY IMAP4 IMAP4REV1] perdition ready on mail.plus.net 00029c87
1 logout
* BYE IMAP4 server logging out, mate
1 OK LOGOUT
Connection closed by foreign host.

(Its common for the actual IP address to change between typed commands as both servers have multiple addresses)

For completeness my traceroutes look like this

$ traceroute smtp.plus.net
traceroute to smtp.plus.net (212.159.9.107), 30 hops max, 60 byte packets
 1  OpenWrt (192.168.1.1)  0.570 ms  0.637 ms  0.701 ms
 2  195.166.130.249 (195.166.130.249)  21.645 ms  23.590 ms  24.961 ms
 3  gi2-23-442.ptn-gw02.plus.net (84.93.253.75)  24.552 ms  25.590 ms gi2-1-444.ptn-gw01.plus.net (84.93.253.79)  27.031 ms
 4  * * *
 (same lines repeated)
 9  * * *
10  195.166.129.160 (195.166.129.160)  14.447 ms !X * *

(!X means "communication administratively prohibited")

$ traceroute imap.plus.net
traceroute to imap.plus.net (217.46.26.18), 30 hops max, 60 byte packets
 1  OpenWrt (192.168.1.1)  0.565 ms  0.666 ms  0.791 ms
 2  195.166.130.249 (195.166.130.249)  20.677 ms  21.521 ms  22.266 ms
 3  gi2-23-442.ptn-gw02.plus.net (84.93.253.75)  23.822 ms  25.748 ms  26.631 ms
 4  * * *
 (same line repeated)
30  * * *

I get the same result from a test USA IP (199.175.48.z) to Plusnet SMTP & IMAP - no response to pings/traceroute but service reachable fine.

So perhaps not being able to ping them might be unrelated to your problem?

[#12]

Plusnet mail servers do not respond to pings (or tracery) by design so as a diagnostic approach it is not productive.

Why do you think the servers are not responding?

Few email clients are smart enough to differentiate between and incorrect password and the total inability to reach the server.

If you want to do some useful diagnostics Google accessing IMAP and SMTP servers using telnet. That will prove for sure if you have a connectivity or a password issue.

Is there by chance a VPN involved here?

[#13]

Thanks @seebee that is really useful.  Now downloading an iOS Telnet app...

[#14]

OK, I can telnet to port 143 on imap.plus.net.

Back to the Mail account in the iPhone which was working until yesterday.  Now it gets really weird. If I go into the account settings and change the password for imap so that it is incorrect then when it tries to verify it (still in account settings, not the app) it tells me the username or password I is wrong.  Then I put the correct password back in and it verifies OK, but when I go to the mail app it says imap.plus.net is not responding when trying to fetch mail.  Port is set to 143.  Stranger still I can send mail from the same account (relay.plus.net with exactly the same username & password).

[#15 · Accepted solution]

Are you attempting to connect over WiFi or 4G?

Telnet connecting, the account set up connecting and the email program connecting are not all in teh same pl;aying field!  The Email program on iOS can be tempermental!  Have you tried unlaoding the mail app and restarting it?  Double click HOME and swipe up on the mail program.

Also try doing a hard restart of the iPhone.

Failing that delete the account and recreate it on the iPhone.

I have seen similar on a number of occasions.