On 04/11/2017 07:02 AM, Wietse Venema wrote: > - If the sender's DNS setup is borked, Postfix will lose time doing > DNS lookup for the SMTP client name/address.
One way I minimized this issue was to define a very large cache in the local DNS service for each dedicated incoming mail server. This was in a web hosting shop with roughly 80K domains across a number of CPANEL and PLESK hosts, with a central set of beefy PostFix-running clearinghouse MXes fronting for QMail and Exim.
