### 3.4 URLs

In email software like Rmail, where mail is stored in files, filenames are used to refer to groups of messages. Since IMAIL folders often aren’t files, it is necessary to use a more general kind of reference for folders. To this end, IMAIL uses Uniform Resource Locators (URLs) to refer to folders.2 IMAIL currently supports two kinds of URLs: IMAP URLs and file URLs.

#### Footnotes

### (2)

URLs are defined in RFC 1738 and RFC 2396.