[issue35863] email.headers wraps headers badly

[R. David Murray]

R. David Murray  added the comment:

Well, "display" in the context of email includes looking at the raw email 
serialized as a text file.  This is something one can do in most mailers. I use 
nmh as my mailer, which only shows raw headers, so I myself would be personally 
affected if headers were not normally wrapped at 78 characters when possible :)

The >80 characters issue you mention is fixed by the folder used by the new 
API.  That folder will use encoded words to wrap overlong tokens in text 
portions of headers, which may or may not have been the best decision (jury is 
still out on that one), and for non-text headers it does not put in that /n if 
the word won't fit on the next line if wrapped.  (Or at least its not supposed 
to, so if you find a case where it does, please submit a bug report.)

email.Header is a legacy module and no longer maintained.  And yes, I realize 
it is used by default.  There should be an open issue about going through a 
deprecation cycle to make the new API the default, but I've lost track and have 
no time to push for it myself.

--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue35863] email.headers wraps headers badly

[Jon Ribbens]

Jon Ribbens  added the comment:

I did read the RFCs. I suspect the [CFWS] in the msg-id is for the benefit of 
the references production which contains a list of msg-ids. The 78-character 
suggested line length limit is explicitly noted as being for display purposes, 
and therefore is of little application to headers which are not displayed in 
user interfaces.

Also consider that the Python wrapping code produces "\n ..." when given a 
header that is 80 indivisible characters long, when there is no possibility of 
avoiding a line over 78 characters.

Outlook seems to cope alright with other headers (I tried From and Subject) 
being wrapped like this; I shudder to think what their code must be like in 
order to produce this bug.

--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue35863] email.headers wraps headers badly

[R. David Murray]

R. David Murray  added the comment:

The rules are: lines should be less than 78 characters; and that lines may be 
broken only at FWS (folding whitespace), not in the middle of words.  Putting 
these rules together, you get the result that the email library produces.  
"Conservative in what you send" means *following the RFC rules*, which is what 
the code does.  The failure here is on the Outlook side, which is supposed to 
be being "liberal in what you accept".  Which it is clearly not doing.

In case you want to read the RFCs, which I just reviewed, Content-ID is defined 
to have the same syntax as Message-ID, and Message-Id is defined as 
"Message-ID:" msg-id CRLF, while 'msg-id' is defined as:

msg-id  =   [CFWS] "<" id-left "@" id-right ">" [CFWS]

Which means that a fold is permitted before the id itself.

We could consider an "enhancement" request to cater to Outlook's deficiency, 
since email clients that are actually limited to 78 character lines are 
vanishingly rare these days.  The change would only be made in the new API 
folder, and I myself wouldn't have the time (or desire :) to work on it, but if 
you want to submit an issue as see what the other email team members think and 
produce a PR if the vote is positive, that's fine by me.

Do you know if it is all headers that Outlook has this problem with, or only 
some?  I will admit that it has been long enough since I implemented this that 
I can't confirm that I made sure it was legal to fold *every* header after the 
colon, but I'm pretty sure I did.

--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue35863] email.headers wraps headers badly

[Jon Ribbens]

Jon Ribbens  added the comment:

It is not correct folding. It might not be explicitly forbidden, but it is 
clearly unwise, and is breaking 'conservative in what you send'. Outlook will 
not be the only program that fails to parse Python's output.

--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue35863] email.headers wraps headers badly

[R. David Murray]

R. David Murray  added the comment:

Also note that you might want to switch to the new API, the folder it uses is 
smarter, although in this case I think it will produce the same result because 
it is the "best" rendering of the header under the circumstances.

--

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue35863] email.headers wraps headers badly

[R. David Murray]

R. David Murray  added the comment:

That is correct folding.  The word is too long to fit within the 78 character 
default if put on the same line as the label, but does fit on a line by itself.

If Outlook can't understand such a header it is even more broken than I thought 
it was :(  You can work around the outlook but by specifying a 
longer-than-standard (but still RFC compliant) line length when serializing the 
message.

--
resolution:  -> not a bug
stage:  -> resolved
status: open -> closed
type:  -> behavior

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue35863] email.headers wraps headers badly

[Karthikeyan Singaravelan]

Change by Karthikeyan Singaravelan :


--
components: +email
nosy: +barry, r.david.murray

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue35863] email.headers wraps headers badly

[Jon Ribbens]

New submission from Jon Ribbens :

email.headers can wrap headers by putting a FWS as the very first thing in the 
output:

>>> from email.header import Header
>>> Header("a" * 67, header_name="Content-ID").encode() 
'\n aaa'

i.e. it produces headers that look like this:

Content-ID:
blah

It is unclear to me whether this is compliant with the spec, but there seems to 
be little reason to do this, and good reason not to in that at the very least 
Outlook does not understand such headers. (e.g. if you have an HTML email with 
an inline image referenced by Content-ID then Outlook will not find it if the 
Content-ID header is wrapped as above.)

--
components: Library (Lib)
messages: 334594
nosy: jribbens
priority: normal
severity: normal
status: open
title: email.headers wraps headers badly
versions: Python 3.4, Python 3.5, Python 3.6, Python 3.7

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com