Applicable to:
- Plesk for Linux
Symptoms
- These warnings can be seen in
/var/log/maillogor/var/log/messages:CONFIG_TEXT: dovecot: config: Warning: service auth { client_limit=1000 } is lower than required under max. load (1396)
dovecot: config: Warning: service anvil { client_limit=1000 } is lower than required under max. load (1399) -
Roundcube shows 500 Internal Server Error with the following errors in
/var/log/httpd/error_logfile:CONFIG_TEXT: [fcgid:warn] [pid 12406:tid 140260554016512] [client 203.0.113.2:42198] mod_fcgid: read data timeout in 45 seconds, referer: http://webmail.example.com/
[core:error] [pid 12406:tid 140260554016512] [client 203.0.113.2:42198] End of script output before headers: index.php, referer: http://webmail.example.com/ -
Mail clients might fail to connect.
Cause
The default_client_limit parameter is too low for Dovecot.
Resolution
- Connect to the server via SSH
Note: If direct SSH access to the server is not possible, contact server administrator for further assistance.
- Create
/etc/dovecot/conf.d/10-master.conffile using text editor to changeclient_limitfor all dovecot services:CONFIG_TEXT: default_client_limit = 1500
- Restart dovecot to apply the changes:
# service dovecot restart
Note: If after raising the default_client_limit the same error message still showing up, increase more the limit.
Comments
12 comments
Just as info, the posted resolution will only end in another error if used with the latest Plesk Onyx 17.8.11 on a CentOS 7.5 as you can read here.
Aug 27 20:17:45 cebede dovecot: doveconf: Warning: service auth { client_limit=1000 } is lower than required under max. load (2248)
Aug 27 20:17:45 cebede dovecot: doveconf: Warning: service anvil { client_limit=1000 } is lower than required under max. load (2251)
As you see, it's the same error just with a higher max. load in my maillog and I found this site by searching for a fix. So after following the steps of this resolution, I got this error:
It looks like dovecot doesn't accept a default_client_limit, anyway if it is set in /etc/dovecot/conf.d/10-master.conf or in the dovecot.conf as client_limit like this, which was posted as resolution on another forum:
service auth { client_limit = 10300 unix_listener auth-userdb { mode = 0666 user = vmail group = vmail } } service anvil { client_limit = 10300 }If you will try the second, it will end with that error:
Aug 27 21:04:00 cebede dovecot: doveconf: Fatal: Error in configuration file /etc/dovecot/dovecot.conf line 40: Unknown setting: service { {client_limit
Aug 27 21:04:00 cebede dovecot: doveconf: Error: managesieve-login: dump-capability process returned 89
But the solution to get no errors is quite easy and really simple, there's no need to get a higher client_limit, in fact it's better to reduce the number of clients, which should be able to use the services of IMAP, POP3, IMAP over SSL/TLS or POP3 over SSL/TLS at the same time. If your client_limit is set to 1000 (Plesk's default), reduce it around 2/3 to 350, may depend on your server, but in my case this will work and you get rid of the errors.
Hi Michael Mahlke,
I checked that solution from this article helped several our clients. For this reason I will not change it.
Probably in your case also resolution from https://support.plesk.com/hc/en-us/articles/115000155573 could help.
Thank you for provided solution.
Hi @Pavel Rozental,
I just tried the solution provided in this article (in my case the requested limits were a bit bigger than 2200). Thus, I set the default_client_limit to 2300. However, now I get the error message as stated by Michael:
So it seems that your article does not help yet - at least for Plesk 17.8.11.
Hi b_p,
> However, now I get the error message as stated by Michael:
Did you try solution from https://support.plesk.com/hc/en-us/articles/115000155573 ?
Well, the article is not available?!
Hello,
I did not notice that it's internal article
For "d limit (ulimit -n)" could you check this solution.
For RHEL/CentOS :
Add the following line in the end of/etc/sysconfig/dovecot:ulimit -n 1200
For Debian/Ubuntu :
Add the following line in/lib/systemd/system/dovecot.servicein[Service]section:LimitNOFILE=1400
Note: the
ulimit -nandLimitNOFILEvalues should be equal or more thandefault_client_limitone.# systemctl daemon-reload
# service dovecot start
My ubuntu server has LimitNOFILE=65535 and I still get the client_error from time to time.
I think increasing any limit just tackles the symptoms, not the cause.
So I'd rather like to reduce the number of allowed simultaneous connections to my mail services.
I do not know how I can do this though.
Hello @Peter,
To reduce the number of allowed simultaneous connections, please navigate to Plesk > Tools & Settings > Mail Server Settings and set required value for Maximum number of connections (IMAP, POP3, IMAP over SSL/TLS, or POP3 over SSL/TLS).
More information about this option you can also find here: Configuring Server-Wide Mail Settings
I have many years experience with other web servers, and I have to say moving to Plesk recently has been extremely frustrating. Some days I'm nearly in tears because my other tasks are piling up while I'm tracking down bugs like this one. I'm not a sys admin, I'm a web developer who always manages the server (and it's NEVER been this hard!) Usually when I have an issue, I can do a web search, read a little bit, and fix it, no problem. And the issues weren't frequent.
For the past month it has been a daily task to check to make sure everything is working and track down issues. I'm so frustrated!
Ok - rant over -
There are different methods of handling this issue listed above, and I'm not sure which way to go. Can someone please help? CentOS and Obsidian 18.0.28. Here's a snippet of my maillog from today:
Jul 28 15:43:54 1112381-server postfix/postfix-script[16787]: refreshing the Postfix mail system
Jul 28 15:43:54 1112381-server postfix/master[14912]: reload -- version 3.4.8, configuration /etc/postfix
Jul 28 15:43:54 1112381-server postfix/anvil[16516]: statistics: max connection rate 1/60s for (smtp:(redacted)) at Jul 28 15:42:16
Jul 28 15:43:54 1112381-server postfix/anvil[16516]: statistics: max connection count 1 for (smtp:(redacted)) at Jul 28 15:42:16
Jul 28 15:43:54 1112381-server postfix/anvil[16516]: statistics: max cache size 5 at Jul 28 15:42:56
Jul 28 15:43:54 1112381-server dovecot: master: Warning: Killed with signal 15 (by pid=16826 uid=0 code=kill)
Jul 28 15:43:54 1112381-server dovecot: service=imap, user=(redacted), ip=[(redacted)]. Server shutting down. rcvd=124, sent=1238
Jul 28 15:43:54 1112381-server dovecot: service=imap, user=(redacted), ip=[(redacted)]. Server shutting down. rcvd=124, sent=1081
Jul 28 15:43:56 1112381-server dovecot: master: Warning: service auth { client_limit=1500 } is lower than required under max. load (2248)
Jul 28 15:43:56 1112381-server dovecot: master: Warning: service anvil { client_limit=1500 } is lower than required under max. load (2251)
Jul 28 15:43:56 1112381-server dovecot: master: Dovecot v2.3.10.1 (a3d0e1171) starting up for imap, pop3, sieve (core dumps disabled)
Jul 28 15:43:56 1112381-server dovecot: config: Warning: service auth { client_limit=1500 } is lower than required under max. load (2248)
Jul 28 15:43:56 1112381-server dovecot: config: Warning: service anvil { client_limit=1500 } is lower than required under max. load (2251)
Jul 28 15:43:56 1112381-server dovecot: master: Warning: Killed with signal 15 (by pid=16885 uid=0 code=kill)
Jul 28 15:43:57 1112381-server dovecot: master: Warning: service auth { client_limit=1500 } is lower than required under max. load (2248)
Jul 28 15:43:57 1112381-server dovecot: master: Warning: service anvil { client_limit=1500 } is lower than required under max. load (2251)
Jul 28 15:43:57 1112381-server dovecot: master: Dovecot v2.3.10.1 (a3d0e1171) starting up for imap, pop3, sieve (core dumps disabled)
Jul 28 15:43:57 1112381-server dovecot: config: Warning: service auth { client_limit=1500 } is lower than required under max. load (2248)
Jul 28 15:43:57 1112381-server dovecot: config: Warning: service anvil { client_limit=1500 } is lower than required under max. load (2251)
Jul 28 15:43:58 1112381-server dovecot: master: Warning: Killed with signal 15 (by pid=17019 uid=0 code=kill)
Jul 28 15:43:59 1112381-server dovecot: master: Warning: service auth { client_limit=1500 } is lower than required under max. load (2248)
Jul 28 15:43:59 1112381-server dovecot: master: Warning: service anvil { client_limit=1500 } is lower than required under max. load (2251)
Jul 28 15:43:59 1112381-server dovecot: master: Dovecot v2.3.10.1 (a3d0e1171) starting up for imap, pop3, sieve (core dumps disabled)
Jul 28 15:43:59 1112381-server dovecot: config: Warning: service auth { client_limit=1500 } is lower than required under max. load (2248)
Jul 28 15:43:59 1112381-server dovecot: config: Warning: service anvil { client_limit=1500 } is lower than required under max. load (2251)
Jul 28 15:43:59 1112381-server dovecot: master: Warning: Killed with signal 15 (by pid=17065 uid=0 code=kill)
Hi Kathy Sechrist please open a support ticket with us here https://support.plesk.com/hc/en-us/articles/213608509-How-to-submit-a-request-to-Plesk-support- so we can troubleshoot the issue. If this did not help there is clearly something else.
Thanks Julian. I am not sure how, but these errors went away. Sorry I didn't see your reply sooner - I'm chasing down new issues almost every day!
Hello, I apply this solution and now my log increase too from 1000 < 2408 to this --> { client_limit=200000 } is lower than required under max. load (402484) and service continues shouting down, I was wondering if this is normal?
Each time I increase this number my max load goes to the double.
Best Regards
Emmanuel
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