How do spammers get into an email account?

[Alek Trishan]

I notice a lot of spam that seems to be from members of my community,
particularly from people with AOL accounts.

Have the spammers gotten their usernames and passwords? If so, how do
they do it, and how can it be prevented?

Thanks.

[Anonymous]

A trojan infects their PC, and takes control. The PC is then part of
a botnet, giving the person who controls it part of a supercomputer,
in effect. That evil bastard then sells computing time on the botnet
of stolen cpu cycles.

Although the malware can use a keyboard logger and harvest usernames
and passwords, it's not necessary for email because they can simply
forge the From: field to send spam (which is generally what happens).