Horde webmail with more than 100.000 emails in one folder or subfolder cannot load messages with the following error:
CONFIG_TEXT: Error when communicating with the mail server
Tunning IIS FastCGI Settings using steps from this article did not resolve the issue
The cause is not clear
For Horde 5.0 and later: Contact Horde Technical Support for assistance.
As a workaround, perform one of the following:
- Clean up unnecessary emails from mailbox and split emails into different subfolders using filters
- Use MailEnable webmail as an alternative to Horde
For Horde 4.x and earlier: set "$conf['server']['sort_limit']" value in %plesk_dir%webmail\horde\horde\config\conf.php file:
Changing 'sort_limit' option in 5.0 and later versions will not take affect because it was discontinued (dropped) starting from Horde 5.0.