Software Quality Research Library

White listing is a process that an ISP or inbox provider uses to distinguish the best senders from the merely good, mediocre or downright bad. Senders who pass rigorous requirements that vary across ISP can get their Internet Protocol address--the address from which they send email--placed on that ISP's white list. This special status confers deliverability advantages, such as bypassing some spam filters and increasing allowable per-hour and/or per-send volumes, over non-white-listed senders. It dramatically improves the chances that messages will be placed in the inbox versus being blocked or routed to junk or spam folders, and that they will arrive with images intact.