238165 - 8bit CTE is used in plaintext part of plaintext + html (multipart) message although in the header (Content-Transfer-Encoding) is set to base64

Status: RESOLVED FIXED

(MailNews Core :: Composition, defect)

Description

[Jungshik Shin]

Spun off from bug 234597 comment #6.

When Mozilla-mail/TB is configured to use 'quoted-printable' for outgoing
messages with 8bit characters and plain text + html format is selected, the
plain text part of the message has 

Content-Transfer-Encoding: base64 
(if there are enough number of 8bit characters to make base64 more
space-efficient), but the actual content-transfer-encoding used is 8bit. This
mismatch makes the plain text part unreadable when read by a mail program that
can't deal with html part.

Observed in TB 0.5 and Mozilla trunk

Comment 1

[Damian Yerrick]

Should Mozilla's mail engine send base64 for text/plain at all?  Popular
spam-blocking software run on ISPs' servers assigns a high "spamminess"
score to text/plain encoded with base64 because for a few months, spam
tended to use base64 to evade content-based filters that had not yet
upgraded to grok base64.  Do we want to see "Mail sent in non-Latin
scripts is often blocked as spam" evangelism bug reports?

Comment 2

[Jungshik Shin]

(In reply to comment #1)
> Should Mozilla's mail engine send base64 for text/plain at all?  

That's a valid question, but this bug is not about that. 

>  Do we want to see "Mail sent in non-Latin
> scripts is often blocked as spam" evangelism bug reports?

I guess so. 'base64' factor can be taken into account by spam blocking programs,
but should not be given such a high 'spamness' score. (spam blocking programs
should be able to decode base64 part.) It's not just mozilla but Pine (and
probably other mail programs) that use base64 for text/plain messages with high
percentage of 8bit characters.

Comment 3

[Jungshik Shin]

This is a rather serious bug and needs to be noted in the release notes. A
work-around is to turn off 'use quote-printable' if one's preferred format of
outgoing messages is 'multipart' (html + plain). 

Comment 4

[Jungshik Shin]

Attachment: patch

this is a trivial patch.

Comment 5

[Jungshik Shin]

Comment on attachment 151430 [details] [diff] [review]
patch

This patch just does for Base64 what's done for QP.

Comment 6

[Jungshik Shin]

Thanks for r/sr and committing to aviary-1.0 branch. Fix checked into the trunk.

Comment 7

[Jungshik Shin]

Comment on attachment 151430 [details] [diff] [review]
patch

asking for a1.7.1
This was fixed on aviary-1.0 as well as on trunk. 

It's a trivial fix that does for base64 what's done for quoted-printable.  It
seems like somehow base64 case was not taken care of when this part was
originally written.

Comment 8

[Mike Kaply [:mkaply]]

Comment on attachment 151430 [details] [diff] [review]
patch

a=mkaply

Comment 9

[Jungshik Shin]

Thanks for a. It's fixed in 1.7branch.

Comment 10

[Scott MacGregor]

I also fixed this on the 0.7.1 branch