Mmencode

Translate to and from mail-oriented encoding formats

From the man page

The mimencode program simply converts a byte stream into or out of one of the standard mail encoding formats defined by MIME, the proposed standard for internet multimedia mail formats. Such an encoding is necessary because binary data cannot be sent through the mail. The encodings under- stood by mimencode are preferable to the use of the uuencode/uudecode pro- grams, for use in mail, in several respects that were important to the authors of MIME.

Mmencode is part of metamail, and can be installed as part of that package. It is provided here as an independent package since some programs require mmencode only and hence you can avoid having to install the entire metalmail package when not required.