I'm having some problems on my courier mail server today what are probably dictionary spam attacks on one or more of the domain names I host. The network connections table fills up with dozens of partially completed SMTP network sessions and after a while the SMTP server just locks up and won't accept any more connections.

To solve this I'm ramping down some of the default timeouts which can be spec'd in files such as esmtptimeout and others like it. The doc for esmtptimeout states the file contains a single text number which specifies the timeout in seconds unless a "m" or "h" is appended to it to specify minutes or hours. Does this format also apply to other similar files such as esmtptimeouthelo and esmtptimeoutdata? The documentation doesn't define the format for these files other than that they "contain one line of text that specifies the timeout".

I'd also like to have the option to drop SMTP connections outside of the LAN for which the IP address of the connecting host has no PTR record and won't reverse resolve to a name. Is there any way to do this in Courier?