IMAP very slow on large mailboxes

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Joined: Mon Jun 01, 2020 11:59 am

IMAP very slow on large mailboxes

Post by DeadMeat038 » Mon Jun 01, 2020 12:44 pm

I'm having issues with some users that have large mailboxes and IMAP taking a very long time to synchronise.

Outlook (Office 365 and Office 2019) performs it's "Send and Receive" and takes a very long time to do so. When it finishes the inboxes don't appear to have updated at all and new mail is not showing at all.

Suddenly on one of the synchronisations the new email appears but this is incredibly intermittent and unreliable.

Often the "Send and Receive" will also timeout and the process has to be started again.

The mailboxes in question are around 35gb.

I have already performed the below steps to no avail:
  • Set maximum concurrent client connections to 20, 50, 100 and even unlimited - no difference
  • Deleted the "index.xml" file for the mailbox and restarted server (as per some other posts in the forum) - no difference
  • Ensured that MailEnable is running the latest version 10.30
Is there anything else that I can do to stop this awful delay with IMAP?

Thanks in advance

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