[Dovecot] Change/add mail header via IMAP

[Timo Sirainen]

On Mon, 2011-04-04 at 19:40 +0400, Алексей Сундуков wrote:
> May be if save mail in new file it can break index dovecot files,
> because file name change? 

If the filename changes, it becomes a new mail. You don't break index
files, but clients see it as a new message.

> Mail is text file, if I add one line (like
> X-Mozilla-Keys: test) how its can break mail?

IMAP protocol requires that mails never change. Clients might cache the
message's size, and when it suddenly becomes larger they might not
download the entire message. Things like that.

Why do you want to modify existing messages anyway?