AIX: How do you send an attachment via mail

Uuencode is the answer:
uuencode [source-file] [filename].b64 mail -v -s “subject” [email-address]
For example:
# uuencode /etc/motd motd.b64 mail -v -s “Message of the day” email@hostname.comI
use the .b64 extension which gets recognized by Winzip. When you received your email in Outlook, you will have an attachment, which can be opened by Winzip.