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Re: Very Slow Email Delivery

Posted: Fri Feb 14, 2020 1:20 am
by combrolegit
zimico wrote:Your system parameters seem to be normal. Is mail flow ok now?
Best regards,
Minh.


Yup the mail flow is very ok now, fyi the current mailbox of my zcs single server is about 1037 mailboxes, with 8 core processor and 32 G of RAM, is the mailbox too much? or there might be parameter that I can adjust so that my zcs can provide good services to 1037 mailboxes? thanks.

Re: Very Slow Email Delivery

Posted: Fri Feb 14, 2020 2:36 am
by zimico
it depends on mail usage of our users. single server with about 1000 mailbox is not too big.
Note that if you started with small server and have added RAM later, you must reconfig innodb_buffer_pool_size and java_heap, please refer to
https://imanudin.net/2019/05/16/zimbra- ... ading-ram/
https://wiki.zimbra.com/wiki/Performanc ... eployments

In my experience, maybe sometime you are under SMTP attack so it will eat your zimbra resource while CPU and RAM is normal.

Best regards,
Minh.

Re: Very Slow Email Delivery

Posted: Fri Feb 14, 2020 7:54 am
by combrolegit
zimico wrote:it depends on mail usage of our users. single server with about 1000 mailbox is not too big.
Note that if you started with small server and have added RAM later, you must reconfig innodb_buffer_pool_size and java_heap, please refer to
https://imanudin.net/2019/05/16/zimbra- ... ading-ram/
https://wiki.zimbra.com/wiki/Performanc ... eployments

In my experience, maybe sometime you are under SMTP attack so it will eat your zimbra resource while CPU and RAM is normal.

Best regards,
Minh.


How to identify that? I believe it only can be done when it's happening, or maybe any way to identify SMTP attack after?

Re: Very Slow Email Delivery

Posted: Fri Feb 14, 2020 3:14 pm
by zimico
Hi,
Use those commands as I already referred in previous posts:

Code: Select all

# cat /var/log/zimbra.log | grep -Eo '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'| sort | uniq -c | sort -nr
# netstat -np --protocol=inet | grep ESTABLISHED | grep :smtpd

Regards,
Minh.