Postfix 2.9 Upgrade
To help reduce the load on my Postfix mail servers, I rely on Postscreen (which is built in to Postfix) to help weed out bot spam and misconfigured mailers. And to reduce the load on Postscreen, one of my tricks is to whitelist the outbound IP addresses of a couple of […]

Postscreen Whitelisting of SMTP Outbound IP Addresses from Large Webmail ...

Yahoo and Postfix 26
If you’re getting “temporarily deferred” Postfix log entries when trying to send mail to Yahoo! that look like this: host[] refused to talk to me: 421 4.7.0 [GL01] Message from ( temporarily deferred - 4.16.50. Please refer to or status=deferred (host[] said: 451 Resources temporarily unavailable. […]

How-To: Postfix configuration to reduce Yahoo temporary deferrals using Transport ...