Types of spam:

• MOOmail: it is considered very poor MOO manners and a waste of data base resources to cross post. Most MOOers get very cranky indeed when they have to slog through trivial, meaningless posts and do the necessary housekeeping, deleting old messages to keep their quota under control.
• MOO *lists: same as the above. It is not necessary to CC users when responding to a MOO list. MOO *lists are stored on the MOO server, and can take enormous resources. MOO *lists cannot be deleted by any but the owner. Some MOOs are moving toward disk bashing of MOO lists, particularly spammy lists.
• Spoofing: sending "unattributed" lines of text runs the continuum from silly and playful to downright dangerous as noted in Julian Dibbell's well known article, A Rape in Cyberspace or How an Evil Clown, a Haitian Trickster Spirit, Two Wizards, and a Cast of Dozens Turned a Database Into a Society.
• MOO spam: spamming the MOO with forked tasks which eat up the proccesses are not only extremely annoying as they lag the MOO, but can cause damage. Purposely folk bombs are considered a taodable offence by many wizards as they can cause the MOO to "crash."