# MIME Formatting
by Brent Welch

If you are familiar with mhn directives, you can enter them into your message. Select the `Attempt MHN` checkbox item under the `More...` menu. You may want to disable `Format mail` to make sure that long mhn directives are not chopped into multiple lines at the wrong places.

To create a multipart MIME message interactively, use the `Insert Part...` menu item. This adds another part to your message and promotes it to MIME content-type multipart/mixed if necessary. The first time you add a part, you have the option of preserving the existing message body or completely replacing it. When the file is inserted you are asked to choose its MIME `Content-type:` and `Content-transfer-encoding:`.

The `Insert External...` menu entry is used to create a MIME part of content-type message/external-body. This is an indirect reference to a file -- either a local file or a file available via anonymous FTP. A dialog lets you fill in the various parameters to the indirect reference. For an anonymous FTP pointer, the `Site` is the Internet host name, and the `Directory` and `File name` determine the file. The `Transfer mode` is either "text" or "image." Use "image" to ensure that all 8 bits of each byte get transferred. The `Description` is for the person who receives the mail message; it should describe what the external part contains.

Tip: A file section dialog appears first, but this is not always appropriate if you are making an external reference to a non-local FTP site. Just hit `Cancel` on the file selection dialog. Then, when you enter the file name, the content-type will be inferred from the name. You can always override the content-type if exmh guesses wrong.