cyrus-imapd with lmtpd + postfix slow delivery with group email ids

[Dan White]

On 05/14/15 05:42 +0000, jayesh.shinde wrote:
>Please suggest , for faster delivery  what could be the best config  in
>postfix + cyrus-imapd .
>
>I am using the cyrus-imapd-2.4.17-6.el6.x86_64 for mailbox server and for
>smtp server postfix-2.10.0-1.el6.x86_64 Both server have SAS hdd , 16 core
>, 16 GB RAM .  There is no i/o issues

>Mailbox server have  21K email ids.  Cyrus running with  tcp socket on
>port 24 i.e lmtpd .  cyrus singleinstance is maintained

>For group id mapping is under virtual_alias_maps of smtp's main.cf  i.e no
>/etc/aliases. From smtp server emails are getting deliver by
>transport_maps to mailbox server .

>My problem observe :--
>--------------------------
>1) When HOD send email to 3-5 big group  email ids then , then its postfix
>delivery get slow. What I observe is postfix getting delivered the traffic
>per email and not parallel.   Each group contain 3k or 7k email ids.

Verify that single instance store is working. If not, you may have a
Postfix configuration issue. Find one of these mass emails in a mailbox and
stat it to find out:

stat -c %h <file>

A returned value of 1 means single instance store isn't working.

If that's not the issue, you can determine if this is a postfix issue or a
cyrus issue by sending a mass email directly to lmtpd, with lmtptest.

>In peak hours the queue on postfix get high and other normal emails also
>getting stuck in queue. Once the group email get clear after that other
>emails also get clear.

>in mailbox cyrus.conf :-- lmtp  cmd="lmtpd -a" listen="lmtp" prefork=0
>in main.cf of smtp server :--
>lmtp_destination_concurrency_limit = 100
>lmtp_destination_recipient_limit = 0

How many lmtp processes do you see spawned in this scenario?

-- 
Dan White