From the definition of wikipedia, Spam is the use of electronic messaging systems (including most broadcast media, digital delivery systems) to send unsolicited bulk messages indiscriminately. While the most widely recognized form of spam is e-mail spam, the term is applied to similar abuses in other media: instant messaging spam, Usenet newsgroup spam, Web search engine spam, spam in blogs, wiki spam, online classified ads spam, mobile phone messaging spam, Internet forum spam, junk fax transmissions, social networking spam, television advertising and file sharing network spam.
For my opinion, spam is a message that sending by anonymous user which is pretending to be official staff of certain organization to trick owners e-mail to get an important information for example user's ID, password, national identification number to be use for many purpose.
Below is example of E-mail spam that I got. Actually, I don't have maybank account which is how can they say my maybank account have problem?
Click image to zoom in.
Actually, spammers target all e-mail user whether they have bank account or not. They just try and error.
For all bank account user's information, bank staff will not asking user's ID and password. So, keep your own ID and password save from anyone.