General recommendations on setting memory limit for Quest Mail, Calendar and Public Folder (4266110)

In some situations you may experience unexpected behaviors of Quest mail and public folder agents and the following errors may be logged:

"Error 3035 System resource exceeded."
"Microsoft Visual C++ Runtime Library: Runtime Error! <Quest Agents executable file name.> The application has requested runtime to terminate it in an unusual way. Please contact the applications support team for more information."

Native MAPI code may experience minor memory leaks. However, when the number of mailboxes or public folders to be synchronized is big, small memory leaks are accumulated which in turn leads to an unexpected system behavior.

Therefore general recommendations on setting the agent's limit on the properties of Agent Host Servers in Project Manager under General-Resource Usage are:

1. Always set memory limit for the agents on particular Agent Host server.
2. Set memory limit to the value which is 10-15% more than the memory size consumed by the agent right after it was started. You can see it in Windows Task Manager by looking at the current memory size consumed by the agent's process.

If the limit is set and the agent's process reaches it, the agent just restarts itself to free up memory used and continues to synchronize mailboxes (or public folders) from the point it has stopped at. At this moment the following error is logged which is considered normal agents behavior:
"The agent's system memory limit 128000 Kb has been exceeded. Agent will be terminated."
The termination itself is graceful where agent closes all PST files and sends them to NTA, closes all MAPI sessions and any opened agent's databases, and only then restarts itself.

IMPORTANT:
1. Quest doesn't recommend exceeding 512 Mb memory limit setting on the agents
2. By default the limit is set to 128000kb.
3. The above logic applies to all memory settings and not just when the memory is set to 64 Mb.