SMTP "451 4.7.1 Try again later" SMTP responses

Support
1

NethServer Version: 7.9
Module: Mail

Hi,

It seems my Nethserver is having trouble with receiving emails. My SMTP provider has confirmed they are seeing the following issues.

Scenario 1: We get no responses (timeout) when we try to connect to your mail server (Checked with tcpdump)
Scenario 2: We get a “451 4.7.1 Try again later” SMTP responses from your mail server

I’m not a Linux guru at all so would be grateful for someone to point me in the right direction on how to investigate this?

Thanks

John

2

@kiemosan

Hi John

Even for a UNIX Guru, it’s not possible to help without more information…

Maybe how is your NethServer connected to the Internet, is it acting as firewall / gateway (2 NICs)?
What technology are you connected with (DSL, Cable, Fiber), and do you have a fixed (static) IP?
Also important: Is there any other box between your NethServer and the Internet, eg a “provider” supplied box?

My 2 cents
Andy

3

Hi,

Single nic VMware hosted Nethserver sits behind my router/firewall with relevant ports forwarded. DSL with dynamic IP but I have dns service set to update my hostname with my current IP. MX does to my dynamic dns hostname.

Simple setup and has worked pretty flawlessly for a long time. Nothing changed recently config/setup wise but I did apply some updates on the 21st.

I’m getting mail through, just not all of it.

Thanks
John

4

Does the IP change have anything to do with it?
How often does the IP change anyways?

I also have clients with dynamic IP, like I use myself at home. But my Home IP does not change often or ever…

5

No IP hasn’t changed for a while and i’ve got a really low TTL (like 5 mins) on the MX for my domain.

6

I think its a greylisting issue with postfix/rspam possibly after Googling that error message.

1 Like
7

Is there any pattern when mail works and when not?
Daily or how often does it “seem” to work and how often not?

If you do not use monitoring tools, there are external monitor tools, eg just to test smtp, important for recieving mail…

8

Does deactivating rspam help (at least for testing…)

9

I monitor using my PRTG install at work and that isn’t reporting any SMTP errors.

10

PRTG?

I know about that, but never used it myself.

But maybe try telnet tests when at work?

11

I’ve switched off Antispam and Antivirus in the application settings in Nethserver. DO I need to do anything else to disable rspamd?

PRTG checks for an available SMTP service on my ip. I’m IT for a company in UK but on the windows side.

12

There is a rspam service to be found under services…
Deactivate it there also, and test if you’re still available (Use a telnet IP 25, as you could see possible errors there…)
If you don’t have telnet on windows, PuTTY is your friend. It can not only handle SSSH, but also the older telnet, often used to troubleshoot E-Mail…

My 2 cents
Andy

PS: Whereabouts in the UK, if I may ask?

13

Thanks, just had to go walk the dog. Nottingham in the UK. I’m familiar with putty for the small bit of Linux admin I do.

I’ll see what disabling the service does and report back.

14

Disabling the rspamd service is giving our SMTP provider 4.7.1 service unavailable errors now and is not accepting any emails.

15

Maillog is the clue we need, if clamd is not available when you received an email, then we could have a try again later

As ever give us the log transaction from helo of postfix to the end of an email transaction

16

Hi Stephane,

From the client side or from the server side?

Thanks
John

17

Server side in /var/log/mailog

18 
Feb 21 07:58:56 nethserver postfix/smtpd[10425]: connect from uk1-rack-lon2.inumbo.com[162.13.166.7]
Feb 21 07:58:56 nethserver rspamd[2703]: <35aaa9>; proxy; proxy_accept_socket: accepted milter connection from /var/run/rspamd/worker-proxy port 0
Feb 21 07:58:56 nethserver postfix/smtpd[10425]: 9EA57E3889: client=uk1-rack-lon2.inumbo.com[162.13.166.7]
Feb 21 07:58:56 nethserver rspamd[2703]: <35aaa9>; milter; rspamd_milter_process_command: got connection from 162.13.166.7:59881
Feb 21 07:58:56 nethserver postfix/cleanup[25150]: 9EA57E3889: message-id=<9DSH2-7OHVqkLTz-9YQu-12PFe6NoEjwQY9cTsb@email.hush-newsletter.com>
Feb 21 07:58:56 nethserver rspamd[2703]: <35aaa9>; proxy; rspamd_message_parse: loaded message; id: <9DSH2-7OHVqkLTz-9YQu-12PFe6NoEjwQY9cTsb@email.hush-newsletter.com>; queue-id: <9EA57E3889>; size: 85045; checksum: <1da384755e531b09c9ce9e66d1e8d9ef>
Feb 21 07:58:56 nethserver rspamd[2703]: <35aaa9>; proxy; rspamd_mime_part_detect_language: detected part language: en
Feb 21 07:58:56 nethserver rspamd[2703]: <35aaa9>; proxy; rspamd_mime_part_detect_language: detected part language: en
Feb 21 07:58:56 nethserver rspamd[2703]: <35aaa9>; lua; greylist.lua:271: greylisted until "Sun, 21 Feb 2021 08:02:56 GMT" (meta and body)
Feb 21 07:58:56 nethserver rspamd[2703]: <35aaa9>; proxy; rspamd_add_passthrough_result: <9DSH2-7OHVqkLTz-9YQu-12PFe6NoEjwQY9cTsb@email.hush-newsletter.com>: set pre-result to 'soft reject' (no score): 'Try again later' from greylist(1)
Feb 21 07:58:56 nethserver rspamd[2703]: <35aaa9>; proxy; rspamd_task_write_log: id: <9DSH2-7OHVqkLTz-9YQu-12PFe6NoEjwQY9cTsb@email.hush-newsletter.com>, qid: <9EA57E3889>, ip: 162.13.166.7, from: <SRS0=8WiP=HX=email.hush-newsletter.com=mail.zvdcabhznfoapnixbqb@srs-uk1.protection.inumbo.net>, (default: F (soft reject): [0.00/20.00] [ASN(0.00){asn:15395, ipnet:162.13.0.0/16, country:GB;},GREYLIST(0.00){greylisted;Sun, 21 Feb 2021 08:02:56 GMT;too early;}]), len: 85045, time: 13.792ms, dns req: 1, digest: <1da384755e531b09c9ce9e66d1e8d9ef>, rcpts: <hazel@REDACTED.co.uk>, mime_rcpts: <hazel@REDACTED.co.uk>, forced: soft reject "Try again later"; score=nan (set by greylist)
Feb 21 07:58:56 nethserver rspamd[2703]: <35aaa9>; proxy; rspamd_protocol_http_reply: regexp statistics: 0 pcre regexps scanned, 0 regexps matched, 184 regexps total, 0 regexps cached, 0B scanned using pcre, 0B scanned total
Feb 21 07:58:56 nethserver postfix/cleanup[25150]: 9EA57E3889: milter-reject: END-OF-MESSAGE from uk1-rack-lon2.inumbo.com[162.13.166.7]: 4.7.1 Try again later;
19 
> Feb 21 08:33:29 nethserver postfix/smtpd[32222]: connect from uk1-rack-lon2.inumbo.com[162.13.166.7]
> Feb 21 08:33:29 nethserver rspamd[2703]: <82ecc9>; proxy; proxy_accept_socket: accepted milter connection from /var/run/rspamd/worker-proxy port 0
> Feb 21 08:33:29 nethserver postfix/smtpd[32222]: D3CF9E3896: client=uk1-rack-lon2.inumbo.com[162.13.166.7]
> Feb 21 08:33:29 nethserver rspamd[2703]: <82ecc9>; milter; rspamd_milter_process_command: got connection from 162.13.166.7:32388
> Feb 21 08:33:29 nethserver postfix/cleanup[1521]: D3CF9E3896: message-id=<44B8.10KZ3.6B1D87FB5800B8326E9VZF5489698ABCD2C709.20210221083327606@r1.dotdigital-email.com>
> Feb 21 08:33:29 nethserver rspamd[2703]: <82ecc9>; proxy; rspamd_message_parse: loaded message; id: <44B8.10KZ3.6B1D87FB5800B8326E9VZF5489698ABCD2C709.20210221083327606@r1.dotdigital-email.com>; queue-id: <D3CF9E3896>; size: 68376; checksum: <39093f49f91060031f1b2929b79e6029>
> Feb 21 08:33:29 nethserver rspamd[2703]: <82ecc9>; proxy; rspamd_mime_part_detect_language: detected part language: en
> Feb 21 08:33:29 nethserver rspamd[2703]: <82ecc9>; proxy; rspamd_mime_part_detect_language: detected part language: en
> Feb 21 08:33:30 nethserver rspamd[2703]: <82ecc9>; proxy; dkim_module_key_handler: stored DKIM key for dkim1024._domainkey.dkim.dotmailer.com in LRU cache for 3600 seconds, 465/2000 elements in the cache
> Feb 21 08:33:30 nethserver rspamd[2703]: <82ecc9>; proxy; dkim_module_key_handler: stored DKIM key for dkim1024._domainkey.dotdigital-email.com in LRU cache for 3600 seconds, 466/2000 elements in the cache
> Feb 21 08:33:30 nethserver rspamd[2703]: <82ecc9>; proxy; rspamd_redis_connected: skip obtaining bayes tokens for BAYES_SPAM of classifier bayes: not enough learns 119; 200 required
> Feb 21 08:33:30 nethserver rspamd[2703]: <82ecc9>; proxy; rspamd_stat_classifiers_process: skip statistics as SPAM class is missing
> Feb 21 08:33:30 nethserver rspamd[2703]: <82ecc9>; lua; greylist.lua:416: greylisted until "Sun, 21 Feb 2021 08:38:30 GMT", new record
> Feb 21 08:33:30 nethserver rspamd[2703]: <82ecc9>; proxy; rspamd_add_passthrough_result: <44B8.10KZ3.6B1D87FB5800B8326E9VZF5489698ABCD2C709.20210221083327606@r1.dotdigital-email.com>: set pre-result to 'soft reject' (no score): 'Try again later' from greylist(1)
> Feb 21 08:33:30 nethserver rspamd[2703]: <82ecc9>; proxy; rspamd_task_write_log: id: <44B8.10KZ3.6B1D87FB5800B8326E9VZF5489698ABCD2C709.20210221083327606@r1.dotdigital-email.com>, qid: <D3CF9E3896>, ip: 162.13.166.7, from: <SRS0=RAXR=HX=r1.dotdigital-email.com=bo-44b8-10kz3-6e9vzf-c16df@srs-uk1.protection.inumbo.net>, (default: F (soft reject): [6.29/20.00] [RSPAMD_URIBL(4.50){ddlnk.net:url;},MANY_INVISIBLE_PARTS(1.00){10;},HTML_SHORT_LINK_IMG_3(0.50){},FORGED_SENDER(0.30){Stauer@r1.dotdigital-email.com;SRS0=RAXR=HX=r1.dotdigital-email.com=bo-44b8-10kz3-6e9vzf-c16df@srs-uk1.protection.inumbo.net;},BAD_REP_POLICIES(0.10){},MIME_GOOD(-0.10){multipart/alternative;text/plain;},HAS_LIST_UNSUB(-0.01){},MX_GOOD(-0.01){},XM_UA_NO_VERSION(0.01){},ASN(0.00){asn:15395, ipnet:162.13.0.0/16, country:GB;},DKIM_TRACE(0.00){dotdigital-email.com:+;dkim.dotmailer.com:+;},DMARC_POLICY_ALLOW(0.00){r1.dotdigital-email.com;none;},FROM_HAS_DN(0.00){},FROM_NEQ_ENVFROM(0.00){Stauer@r1.dotdigital-email.com;SRS0=RAXR=HX=r1.dotdigital-email.com=bo-44b8-10kz3-6e9vzf-c16df@srs-uk1.protection.inumbo.net;},GENERIC_REPUTATION(0.00){-0.32106786437009;},GREYLIST(0.00){greylisted;Sun, 21 Feb 2021 08:38:30 GMT;new record;},HAS_REPLYTO(0.00){re-44B8-10KZ3-6E9VZF-C16DF@r1.dotdigital-email.com;},IP_REPUTATION_HAM(0.00){asn: 15395(-0.13), country: GB(-0.00), ip: 162.13.166.7(-0.32);},MID_RHS_MATCH_FROM(0.00){},MIME_TRACE(0.00){0:+;1:+;2:~;},RCPT_COUNT_ONE(0.00){1;},RCVD_COUNT_TWO(0.00){2;},RCVD_TLS_ALL(0.00){},REPLYTO_DN_EQ_FROM_DN(0.00){},REPLYTO_DOM_EQ_FROM_DOM(0.00){},R_DKIM_ALLOW(0.00){dotdigital-email.com:s=dkim1024;dkim.dotmailer.com:s=dkim1024;},R_SPF_NA(0.00){no SPF record;},TO_DN_NONE(0.00){},TO_MATCH_ENVRCPT_ALL(0.00){}]), len: 68376, time: 372.450ms, dns req: 60, digest: <39093f49f91060031f1b2929b79e6029>, rcpts: <ADDRESSREDACTED>, mime_rcpts: <ADDRESSREDACTED>, forced: soft reject "Try again later"; score=nan (set by greylist)
> Feb 21 08:33:30 nethserver rspamd[2703]: <82ecc9>; proxy; rspamd_protocol_http_reply: regexp statistics: 0 pcre regexps scanned, 3 regexps matched, 184 regexps total, 80 regexps cached, 0B scanned using pcre, 71.12KiB scanned total
> Feb 21 08:33:30 nethserver postfix/cleanup[1521]: D3CF9E3896: milter-reject: END-OF-MESSAGE from uk1-rack-lon2.inumbo.com[162.13.166.7]: 4.7.1 Try again later; from=<SRS0=RAXR=HX=r1.dotdigital-email.com=bo-44b8-10kz3-6e9vzf-c16df@srs-uk1.protection.inumbo.net> to=<ADDRESSREDACTED> proto=ESMTP helo=<uk1-rack-lon2.inumbo.com>
> Feb 21 08:33:30 nethserver postfix/smtpd[32222]: disconnect from uk1-rack-lon2.inumbo.com[162.13.166.7]
> Feb 21 08:33:30 nethserver rspamd[2703]: <2ded99>; proxy; proxy_milter_finish_handler: finished milter connection
20

Hi @stephdl,

Do these logs tell you anything useful? I appreciate your help.

Thanks

John