Hello,
But I'm confusing between Courier-IMAP and Dovecot. Anyone tell me some quick tips regarding this issue. What's the better and what's the worst thing comparing these two IMAP/POP3 servers? I think the Dovecot is good enough for security and performance issue over Courier. Is it right? And how about the feature comparision?
let me tell you from my experience that dovecot is the best imap/pop3 server to start. It is very fast due to its indexes and has more options to configure than Courier and is still very easy to understand and flexible. We once moved from dovecot to Courier because we expected it to work better with NFS, but we decided to move back to dovecot again very soon, because there is no option in Courier to have all imap subfolders in one level, instead everything is below "INBOX." which is not what most people are used to from hotmail.com or Outlook. Also, Courier doesn't have an index which makes it slower. And the mailinglist is not as helpful and friendly as the dovecot-ml. If you plan to check for quotas then you should begin to deliver messages with dovecots local delivery agent. Otherwise summing the sizes of all files in your mailboxes on each delivery of a new message to a mailbox will slow down your machine dramatically if you have a lot of messages and concurrent requests/users.
We have moved to cyrus in between, because it has a lot features that dovecot won't have in the near future (like shared mailboxes or delayed expunge, replication etc.), but it is very hard to set up and makes only sense in big installations. For the start maildirs and dovecot are an ideal setup, easy to maintain and very fast and stable.
Regards Marten