Horde Fetch Email exceeds limits

Need to increase the Fetch email limit for Horde webmail

[Mitch888]

In Horde webmail there is a feature called Fetch Mail to allow Other Mail Accounts to be fetched. When I use this feature to import emails from other servers; I get an error saying: (The message exceeds the fetch size limit).

I am using Windows server with Plesk 7.5.6. Where can I change the so called fetch size limit? Which config file do I need to modify?

Any help would be greatly appreciated!

Thank you
Mitch