[Mimedefang] Dovecot Metadata question

Michiel Brandenburg apex at xepa.nl
Wed Apr 21 11:52:35 EDT 2010

On 21-4-2010 15:36, Kevin A. McGrail wrote:
> Dovecot uses C-Client (ie. UW-IMAP, Pine) compatible headers in mbox
> messages to store metadata. These headers are:
> * X-IMAPbase: Contains UIDVALIDITY, last used UID and list of used
> keywords
> * X-IMAP: Same as X-IMAPbase but also specifies that the message is
> a "pseudo message"
> * X-UID: Message's allocated UID
> * Status: R (\Seen) and O (non-\Recent) flags
> * X-Status: A (\Answered), F (\Flagged), T (\Draft) and D (\Deleted)
> flags
> * X-Keywords: Message's keywords
> * Content-Length: Length of the message body in bytes
> to IMAP/POP3 clients when they read the mail. Preferably your LDA should
> strip all these headers before writing the mail to the mbox.
> So I'm wondering if there is any reason these headers shouldn't be
> stripped for every email on the system by MD?

I don't see a reason not to remove these headers if and only if you are 
using Dovecot. I do not think that another message system (cyrus for 
instance) cares about them headers anyway, and will happily pass them 
along to clients.

If it were my choice I would remove them if Dovecot is used and it uses 
them headers for strictly internal meta data only.  The client will 
never see them even if you do not strip them.  It might only cause 
problems in the future, I would guess, if you do not remove the headers.

On a side note are not X- headers informational only ? So anyone can put 
them in, if you remove them less for spam scanners and the like to use, 
and I prefer to keep email as intact as possible.  I do seem to have 
some spammers using x-status headers in my mailboxes.

And why did dovecot pick these header names could they not have picked
something with a prefix like X-Dovecot-  :)

Michiel Brandenburg

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