From Virtual Entity of Relevant Acronyms (Version 1.9, June 2002) :
UBE
Unsolicited Bulk Email (spam, Internet, UCE)
From Jargon File (4.3.1, 29 Jun 2001) :
UBE // n. [abbrev., Unsolicited Bulk Email] A widespread, more formal
term for email spam. Compare UCE. The UBE term recognizes that spam
is uttered by nonprofit and advocacy groups whose motives are not
commercial.