Another technique was used in late 2007 by the company iDate, which used email harvesting directed at subscribers to the Quechup website to spam the victim's friends and contacts.
The DNS and WHOIS systems require the publication of technical contact information for all Internet domains; spammers have illegally trawled these resources for email addresses.
Spammer viruses may include a function which scans the victimized computer's disk drives (and possibly its network interfaces) for email addresses.
In addition, sometime the addresses may be appended with other information and cross referenced to extract financial and personal data.
A recent, controversial tactic, called "e-pending", involves the appending of email addresses to direct-marketing databases.
[2] Users can defend against such abuses by turning off their mail program's option to display images, or by reading email as plain-text rather than formatted.
Likewise, spammers sometimes operate Web pages which purport to remove submitted addresses from spam lists.
[3] When persons fill out a form, it is often sold to a spammer using a web service or http post to transfer the data.
For instance, if someone applies online for a mortgage, the owner of this site may have made a deal with a spammer to sell the address.
These are considered the best emails by spammers, because they are fresh and the user has just signed up for a product or service that often is marketed by spam.