What are Attachments?

Should links inside emails be considered attachments?  In the technical sense of an email (like rfc 2183) links wouldn’t be considered a different content type.  The question isn’t whether they are technically attachments as much as if they should be attachment-like in the user interface.


Facebook handles links in a message almost like an attachment-object and will do some additional meta work on the link to provide a default photo and short description for it.

In the message list view Facebook offers an icon to note that a link attachment was included in a messages.

In the composition view Facebook also grabs links from inside the message and shows them separately as an attachment like thing.  In the screenshot below the composition window grabbed the link inside my message and pulled down a description and number of photos from the site.

link detected in the composition area

This kind of meta data around a link can be really beneficial.  The presentation of the link is better than a person naturally would and since it’s the information is retrieved automatically it only takes extra seconds  to make sure a good image and description appear.

Beyond just the benefits of better presentation is another hot topic in the Thunderbird world of offline support.  When reading mails offline it’s far better to have a more context about the link than none at all.  Even if I can’t bring up the link in an offline state the image, description and comment can help me to recall what the link is about.


When you’re using the rich editor for composing a message in Gmail and create a link it has some nice features for recognizing a link and helping you edit it.  Here are some screen shots of what Gmail is doing right now.

Popup indicates the link has been recognized in compose window

Editing a Link

Alternatively Editing an Email link

Pretty straightforward and simple stuff when compared to the extra things Facebook is doing.  Gmail doesn’t add meta-data about the links or make their inclusion visible in the message list.

Links as Attachments

If in Thunderbird we wanted to start treating links more like we treat attachments…

  • How do we present that to the user?
    • Both in terms of composing messages and when receiving links in messages.
  • Do we grab meta data for links sent to us?
    • assuming some kind of policy about what links we can do that with
  • And should we be making links available somehow in Firefox?

8 thoughts on “What are Attachments?

  1. I think it’s going to be hard to develop a policy for which links can be scouted, unless it’s some sort of opt-in-by-domain or opt-in-by-sender rule, in which case there’s a problem of making the user aware of the feature. This isn’t a problem in Facebook since the messages are all sent by humans.

    Also, despite guidance to contrary, many systems use HTTP’s GET method to represent actions which modify something (instead of the POST method), like confirming a password reset, removing a Google alert (yep, just tried it :() or similar.

    The consequences of the policy being wrong might be that some sort of action is taken without the user even knowing, maybe even irreversible, so it’s important that it has no false positives.

  2. Not sure this completely what you are asking but… it would be nice if Thunderbird was able to either have a pane or a flyover that gave a preview of the page, and/or document that was “attached”. Right now Thunderbird will give a list of attached filenames, but what if that was a rendered preview of the attachments. In this case, any embedded URL’s could be considered an attachment, and be previewed. Since on most modern widescreens width is more available than height, the preview could be a pane on the RHS. As a continuation, when editing/composing an email, a thumbnail image could be attached and/or other data as the link rather than the traditional URL style link. Certainly any logic related to displaying a link in blue could activate more complex editing tools, maybe changing the toolbar to suit the task. At this point it starts to get into the OpenOffice/MS Word realm, and you should look towards consistency with those.


  3. The large majority of emails I get are from various FOSS mailing list, and usually such mails have a footer containing info and a link about subscribing/unsubscribing. (sometime those links are also inside of the body, because of defective clients/ people not trimming unnecessary parts)

    I would *hate* to have those links standing in my way.

  4. Be careful what you’re doing, following a link from untrusted, potentially malicious content (any of malware, spam or phishing).

    There lie dragons…

    (PS your email verifier + captcha tried to eat my comment)

  5. D’oh. Of course, after properly reading what you wrote (and not just what I thought you’d written), you’re talking about email *composition*.

    In which case, you just need to get round the whole “HTML emails Are Evil(TM)” thing.

  6. I know this has been said already by commenters, but I’d like like to re-iterate:

    Not all links are locations. Some are actions. Fetching metadata for such links will perform those actions. That’s a Bad Thing ™.

    Although, saying that, fetching the favicon for the domain would be safe and handy. Assuming its in the default location.

    But otherwise, I think its a great idea. I’ve never used Facebook, but the ideas presented in those screenshots look good.

  7. The link preview feature looks useful. I would want the links to be listed in their own section of the screen (perhaps under any attachments) and marked as such. Not listed as an attachment. Another optionswould be for the link meta information to be shown in a pop-up window when the cursor is hovered over the link.

    As far as security goes, you would have to apply at least the same level to the retrieved html as is applied to html emails by thunderbird. If you don’t execute javascript and cookies that takes care of a large portion of unintended consequences, but still leaves open having your email validated as good by following a link.

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