yahMAIL Usage Guide

5 - MIME Encoded Messages

[next] [previous] [contents] [full-page]

Messages encoded using Multipurpose Internet Mail Extensions (MIME) allow enriched content (e.g. containing images, audio, multiple fonts), and included attachments (e.g. application-specific, binary files), to be transfered and stored by mail agents within essentially plain-text documents. It can handle one or more components per message, encapsulating each as encoded content.

yahMAIL will process a VMS Mail message body containing a leading RFC822 header that specifies MIME content. It is essentially a minimum implementation rendering descriptive text components in plain text and providing buttons to allow the downloading of non-textual or attachment components. If the descriptive component has an associated charset attribute this character set is used when rendering it.

Generally, if a browser can render the content of the attachment it is displayed within the browser window, etc, or alternatively an independent viewer may be spawned. If it is not configured to process it a save-as dialog is usually presented. A checkbox below the buttons, marked save as file, if checked sets the content-type as binary resulting in the browser unconditionally providing a save-as dialog.

NOTE

The exception to this appears to be Microsoft Internet Explorer, which if it is a "well-known" file extension attempts to render it regardless! As a compromise, the displayed content-type is made a link for MSIE browsers. This allows the user to right-click on the link activating a pop-up menu with a save as option.

Processing of MIME messages is resource intensive. Depending on the number and size of components this may add noticable latency to requests and load to the system.

On some platforms yahMAIL can support sending attachments using MIME (7.5 - MIME Attachments). This can also be accomplished using the browser's own email client (and of course it is possible to have the client's identity configured so as to reflect the user's VMS mailbox if desired).


[next] [previous] [contents] [full-page]