Our system running on multiple servers, and when about 2000 user online concurrent, then users in my system could not send email.
I get these logs on zimbra.log
Jun 17 13:40:48 mta1 saslauthd: authentication against url 'https://mymailboxdomain.com:7073/service/admin/soap/' caused error 'curl_easy_perform: error(28): Operation timed out after 45005 milliseconds with 0 bytes received'
Jun 17 13:40:48 mta1 saslauthd: auth_zimbra: email@example.com auth failed: curl_easy_perform: error(28): Operation timed out after 45005 milliseconds with 0 bytes received
Jun 17 13:40:48 mta1 saslauthd: url 'https://mail.vss.gov.vn:7073/service/admin/soap/' will not be used for (at least) 600 seconds
Jun 17 13:40:48 mta1 saslauthd: Authentication cycle re-elected url https://mail.vss.gov.vn:7073/service/admin/soap/, giving up ...
And this link usually timed out: https://mymailboxdomain.com:7071/service/admin/soap/
(Although I still telnet to mymailboxdomain.com 7071) and this issues gone if I restart zmmailboxdctl, but only in shortly time, it came again.
My mailbox server have 1T RAM, CPU: Intel(R) Xeon(R) CPU E7-8860 v4 @ 2.20GHz 144 core CPU and very much empty
Anyone can help me, I think the problem is that there are too many users at the same time