(Linux) Inline images not showing due to case of CID

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HaydnH
Posts: 7
Joined: February 22nd, 2018, 5:46 am

(Linux) Inline images not showing due to case of CID

Post by HaydnH »

Hi All,

I keep receiving messages with inline images where the case on the cid doesn't match and breaks the inline image, sample below. Is there a way for me to tell Thunderbird that if an inline image references a cid "src=SomeImage.jpg", the mail doesn't have that message part but does have a match for a case insensitive version then show the case insensitive version anyway? I get the feeling this isn't a bug as the RFCs probably state that CID should be case sensitive, so I guess it's a "won't fix" situation...

...
Content-Type: multipart/related;
boundary="----=_Part_64686_991148286.1523354487208"

------=_Part_64686_991148286.1523354487208
Content-Type: multipart/alternative;
boundary="----=_Part_64687_198593023.1523354487208"
...
------=_Part_64687_198593023.1523354487208
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: 7bit

<html><head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="GENERATOR" content="Microsoft FrontPage 4.0">
<meta name="ProgId" content="FrontPage.Editor.Document">
<title></title>
</head>

<body>

<table>
<tr>

<td><img src="cid:HeaderNew.JPG">
...
------=_Part_64687_198593023.1523354487208--

------=_Part_64686_991148286.1523354487208
Content-Type: image/jpeg
Content-Transfer-Encoding: base64
Content-Disposition: inline; filename="headernew.jpg"
Content-ID: <headernew.jpg>
...



Thanks,

Haydn.
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tanstaafl
Moderator
Posts: 49647
Joined: July 30th, 2003, 5:06 pm

Re: (Linux) Inline images not showing due to case of CID

Post by tanstaafl »

I'm not aware of a setting to do that. However, the value of Content-ID: is required to be globally unique. The ones in your example aren't. I'm used to seeing that done by creating a email address using a unique username in hex such as part1.4708CB88.E65453C8@fastmail.fm . It's possible that Thunderbird assumes the value follows that format.

If you only occasionally run into this problem you could edit the contents of an existing message using the HeaderToolsLite add-on at https://addons.mozilla.org/en-US/thunde ... ools-lite/ .

https://tools.ietf.org/html/rfc2392
HaydnH
Posts: 7
Joined: February 22nd, 2018, 5:46 am

Re: (Linux) Inline images not showing due to case of CID

Post by HaydnH »

tanstaafl wrote:I'm not aware of a setting to do that. However, the value of Content-ID: is required to be globally unique. The ones in your example aren't. I'm used to seeing that done by creating a email address using a unique username in hex such as part1.4708CB88.E65453C8@fastmail.fm . It's possible that Thunderbird assumes the value follows that format.

If you only occasionally run into this problem you could edit the contents of an existing message using the HeaderToolsLite add-on at https://addons.mozilla.org/en-US/thunde ... ools-lite/ .

https://tools.ietf.org/html/rfc2392
Thanks for the reply, I saw HeaderToolsLite, unfortunately I receive these emails daily and this would only fix emails after I've read them rather than on arrival before I read them, it would be easier to do that with sed/awk on the command line. I can't seem to find anything to do it as emails arrive, being able to run a script as a mail filter could work but can't find that either, perhaps writing a new extension is the only possibility? :(
User avatar
tanstaafl
Moderator
Posts: 49647
Joined: July 30th, 2003, 5:06 pm

Re: (Linux) Inline images not showing due to case of CID

Post by tanstaafl »

I suggest you try reading those messages using several other email clients (or webmail) to see how widespread the problem is. Perhaps it displays okay only for Microsoft email clients. Then contact the author of the messages.

You could try writing a message filter to fix the CID if you install the FiltaQuilla add-on . However, that could be very difficult.

https://addons.mozilla.org/en-US/thunde ... ltaquilla/
http://mesquilla.com/extensions/filtaquilla/

Does your email provider support advanced server side scripts such as Sieve (a programming language that can be used for email filtering)?
A lot of Cyrus IMAP servers support that. https://en.wikipedia.org/wiki/Sieve_(ma ... _language)

I've read about procmail being used to edit headers, I don't know whether it can do something as advanced as what you want to do. That might also require you to switch to a MoveMail account.
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