SYMPTOMS

Occasionally the web mail application will take up large amounts of memory and CPU for a while and then start to work again. The server is usually running 64bit Windows with the web mail running under ASP.NET 2.0 (in 64bit mode).

CAUSE

If the web mail application is unloaded from memory, either by restarting IIS or recycling the MailEnableAppPool application pool, then the web mail .Net application needs to be compiled again into memory, which can take up resources. Also, earlier versions of MailEnable were not optimised for this environment.

RESOLUTION

Configure the MailEnableAppPool under IIS to turn off "Recycle worker processes (in minutes) under the Recycling options, and the "Shutdown worker processes after being idle for (time in minutes)". This will prevent the application needing to be compiled into memory if those conditions are met. There will still be a compilation time when IIS is restarted though. Upgrade to at least version 2.5/3.1 of MailEnable as changes were made to address this speed issue.