Delivery delay to specific host

[konc...@gmail.com]

We have a postfix instance used to handle AV/AS type functions setup following http://www.postfix.org/FILTER_README.html#advanced_filter this model. In addition to this we setup a transport_map in conjunction with always_bcc to feed a second postfix. The mail being delivered via the bcc seems to be batched approximately every 10s. Looking at logs, it looks like it does the initial concurrency of 5 messages, connections close, and ~10s later sends a large batch. This cycle repeats. Messages sent via the primary path and on to our internal server do not seem to show this batching behavior. Most settings are at defaults. Skipping size/network info changed config lines are below:

disable_dns_lookups = yes
smtp_destination_concurrency_limit = 30
default_transport = smtp:[ip.add.re.ss]:port
local_transport = error:5.3.2 Not accepting local messages
default_destination_concurrency_failed_cohort_limit = 0
default_destination_concurrency_negative_feedback = 0

Queue run/backup times have been tuned to 15s