On Mon, Mar 31, 2014 at 02:44:10AM +0200, li...@rhsoft.net wrote:
> > The way I had assumed it earlier was the client authenticates via
> > 993 (dovecot IMAP in our case), crafts an email to another user
> > and this email is delivered instantly via lmtp (in our case, dovecot
> > LDA), but now I see that in reality, the client sends the email
> > via the smtp port instead making a direct connection with the mail
> > server. Its still secure but the other way sounds more secure.
>
> That explains why your posts sounded that weird...
>
> * IMAP/POP3 -> receive messages
> * SMTP -> send messages
> * LMTP -> LDA
Oddly enough there is a hybrid protocol, in which the SMTP client
talking to a suitable SMTP server asks the SMTP server to retrieve
the message content from the user's IMAP "Outbox", and send that.
Here, the control channel for sending the message is still SMTP,
but the message body is not sent by the client separately to the
SMTP server after uploading it to the IMAP server. This saves
bandwidth on mobile clients, and is used primarily in Apple iOS.
Postfix does not yet support Apple's BURL SMTP extension. With
Apple as the only MUA that supports BURL, it probably does not make
sense for Postfix to support BURL.
Perhaps this is a catch-22, and other MUAs would support BURL if
non-Apple MTAs implemented it. The real problem is that with Web
mail, IM, social media, ... there is very little new development,
in IMAP MUAs. For graphical MUAs we have Outlook, Thunderbird and
Evolution. For curses we have pine, elm, and mutt. None have seen
substantial new protocol features for some time.
It would be great if someone volunteered to add client-side BURL
support to Thunderbird, or DANE TLSA support, especially in
combination with RFC 6186 support.
Similar improvements to pine, mutt, elm, ... would also be great.
--
Viktor.
