Imap servers

From Simson Garfinkel
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Jan 2, 2010 - Review of IMAP Servers

Increasingly I've been having problems with the Dreamhost imap server and its interactions with the Apple application. The problems I've noticed include:

  • A persistent tendency to create INBOX.INBOX.INBOX.INBOX...INBOX inboxes inside my INBOX. This seems to be a bug with interacting with Dreamhost's mail courier mail server.
  • Improper handling of the IMAP NOTIFY extension, so that deletes and moves on my laptop don't get immediately handled on the desktop.

I've reviewed three other imap servers and they all handle push properly.

  • gmail (Google; not sure what they are using)
  • (Apple; seems to be based on the old Netscape code)
  • Pair (dovecot)

One of the reasons to go with a managed imap provider is that they should also be able to provide a good web interface.

gmail imap review

Google's gmail interface. Advantages:

  • Message can be in multiple mailboxes.
  • flag in apple Mail is same as "star" in gmail.


  • Hard to see all of the contents of a mailbox using Google's interface
  • Slow to load in web browser.
  • 3-30 seconds to update.
  • Complains when there are too many simultaneous IMAP connections.
  • Somewhat confusing interaction between inbox in gmail interface and inbox in imap interface.
  • Deleting a message on Mac moves the mail into "Deleted Messages" mailbox, which adds the "Deleted Messages" tag on gmail. But emptying the trash doesn't actually delete the message from the gmail archive, it just removes the tag.
  • "undo" doesn't work on Apple interface after a Delete.

2009-01-08 --- After using gmail's imap server for a week, I'm giving up on it. It's pretty reliable, but I encountered two show-stoppers:

  1. When an IMAP client was disconnected for several days and reconnects, it did not update properly.
  2. Gmail doesn't allow more than 5 or so simultaneous connections to the same IMAP mailbox. Every time I bring my VPN up or down it looks like another connection from another IP address, and gmail locks me out of my mail account. That's not I'm giving up on gmail


  • Instant update


  • Client-side anti-spam and filters. (dovecot)


  • 3 seconds to update.

Dreamhost (courier)


  • Doesn't always update.
  • Arbitrarily archives mail.
  • anti-spam whitelist filtering is based on return-path, which means it doesn't work if you forward all of your email through a service like
  • Some downtime.