Support for SMTP BURL extension (RFC 4468)



11 years ago
4 days ago


(Reporter:, Unassigned)



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11 years ago
When sending a message, the message is sent to both the SMTP server and the IMAP server for storage in the Sent folder. For large messages or low bandwidths, this may take a long time. For people who pay per megabyte internet traffic, e.g. mobile users, this may expensive as well.

RFC 4468 specifies the BURL extension to SMTP that allows clients to store the message in the IMAP server and then refer to it in the SMTP conversation rather then transferring the whole message over the wire again. Thunderbird should use this extension on SMTP servers that support it.

RFC 4468 is currently a Proposed Standard. It is implemented in Sun Messaging Server 7.0:
Component: General → Networking: SMTP
Product: Thunderbird → Core
QA Contact: general → networking.smtp
Product: Core → MailNews Core
what a concept
Keywords: perf

Comment 2

10 years ago
It seems neither postfix nor exim support this yet. In mean time people usually use gmail style copying in IMAP sent folder after message submitted to SMTP and not copy to IMAP from MUA.
1. bcc self:
   In Account Settings... | tab Copies and Folders
   Disable [ ] Place a copy in ... Folder
   Enable [x] Bcc these email addresses: []
2. Filter:
   In Tools | Message Filters..., create a filter that matches
   From, contains,
   Move message to, Sent

This means you'll still transfer the message twice (once upload with SMTP, once download (instead of upload) with IMAP). However, depending on prefs, the attachment is not downloaded, which is typically the big issue. Also, download is often much faster than upload.
This proposal would:
1. Entirely avoid the duplication
2. Avoid the workaround in last comment,
   2.1. ... which users need to know and set up first
   2.2. The workaround might have other side-effects,
        like triggering on some spam which uses your own address as From
        (hasn't been a problem in practice for me, though, although I use
        this method.)

I would wait for Postfix to implement this first, though.

Comment 5

2 years ago
Dovecot just added support in the core code (for 2.3, due to be released before the end of the year) for BURL/URLAUTH thanks to Stephan Bosch.

It would be awesome if Thunderbird could be one of the first clients that made use of it.

Comment 6

4 days ago

Dovecot 2.3 is out since a while already, so client support could be tested against an actual server. Has any progress happened in Thunderbird to implement this?

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