I noticed that our users who use eM Client are getting severely delayed emails via IMAP. I found a solution from the eM Client forum that allows you to add the following parameter under the Menu > Accounts > Diagnostics tab: --imap-avoid-search-by-messageid

If I understand this correctly, using this parameter indicates that SmarterMail isn't indexing some header information, such as message-id, which slows down the operation. That said, is there a way that SmarterMail can index this so that our users don't need to use this parameter in eM Client?