People who want to spread viruses and worms via e-mail, like to hide behind e-mail addresses that appear credible: both people sending spam and phishing mails use this tactic to hide who they really are. It is illegal to send spam in Germany. The more trustworthy spammers appear, the more likely recipients are to actually open the e-mail.

What is going on behind the curtains on the technical stage: Special computer worms misuse e-mail addresses in order to spread; they send themselves to every address they find on an infected system. To do this they search contact folders and HTML files, among other data. Most browsers store websites recently visited for a period of time in a cache, which can become a valuable source of addresses for clever computer worms.

Another tactic for address-fakers are e-mail servers that have not been configured correctly and process any and all e-mail addresses. These can be used to send e-mails with fake senders. An e-mail server that is configured correctly, will send and receive only those e-mails with a certain address range.