A file on a Macintosh computer with the extension ".eml" is a document in plain text containing the complete Internet headers and body of an email message. Mac OS X Mail can automatically handle EML files; you can also open and edit these documents in any word processor or text editor.
EML File Format
- An EML file begins with the Internet routing information and other email header data normally hidden from view in Mac OS X Mail messages. These are followed by the visible headers of an email message, including "From," "To" and "Subject" information. The remainder of the file is the body of the message. Text-only emails display the body without modification, but emails containing HTML, text formatting or attachments use MIME encoding to store this information as plain text. This method is identical to the way email messages are encoded for transmission over the Internet.
Creating EML Files
- You can create an EML file from within Mac OS X Mail by selecting a message and choosing "Save As" from the "File" menu. Select the "raw message source" format to save the message as an EML file. You can also drag any message out of the Mail window, then drop and save it directly to your Desktop folder in EML format.
Opening EML Files
- Double click any EML file to open it in Mac OS X Mail. If the message is not already in your email archives, it is copied to your Mail application and opened. If the message is already stored in that location, the message opens and is not duplicated. Mail interprets an EML file and shows it as a standard email message. Choose "Raw Source" from the View menu under the "Message" submenu to display the file's Internet headers.
Working with EML Files
- Drag the EML file to a word processor or text editor icon in your Dock to open it for editing or viewing. You can also control-click the file, choose "Open With" from the contextual menu and select the application with which you wish to open it. Unlike the Mail application, a word processor or text editor displays the complete Internet headers of the EML file by default, as well as showing the plain-text encoding of the body of the message and any attachments. This makes it more convenient to work directly with the raw source of an email message, to accomplish tasks such as reviewing transmission information in the headers and copying the data to send to someone else. Attachments are converted to encoded text in these documents, however, so you'll want to return to Mac OS X Mail to work with them.
