To demonstrate that the interface provided by MailBox is often quite close to that of other implementation, the above example is included. As you can see, the build method provided by the MIMEtools is not that far away.

Some differences however: where MIMEtools only accepted a restricted list of header fields, MailBox accepts anything which starts with a capital as header field. Lower-cased keys indicate parameters. MailBox has smart defaults for the attachment types provided by MIME::Types, although an attach method to explicitly change the defaults is provided as well.