Import Postfix 2.7.1. Major changes since Postfix 2.6.6:
- Improved before-queue content filter performance. With
"smtpd_proxy_options = speed_adjust", the Postfix SMTP server
receives the entire message before it connects to a before-queue
content filter. Typically, this allows Postfix to handle the same
mail load with fewer content filter processes.
- Improved address verification performance. The verify database is now
persistent by default, and it is automatically cleaned periodically. Under
overload conditions, the Postfix SMTP server no longer waits up to 6 seconds
for an address probe to complete.
- Support for reputation management based on the local SMTP client IP address.
This is typically implemented with "FILTER transportname:" actions in access
maps or header/body checks, and mail delivery transports in master.cf with
unique smtp_bind_address values.