The other annoyance: Unwanted messages, usually commercial or scams
First recorded spam message sent in 1978 "from a DEC marketing rep to every Arpanet address on the west coast"
Later mainly on the USENET groups, before moving back to email
Counter measures such as mass cancelling eg Arnt Gulbrandsen's "cancelbot" were effective
Growing number of email users attracted spammers to email again in late 1990s
Spam messages may very well carry malware