Opt in e-mail

For other uses, see Opt.

Opt in e-mail is a term used when someone is given the option to receive "bulk" e-mail, that is, e-mail that is sent to many people at the same time. Typically, this is some sort of mailing list, newsletter, or advertising. Obtaining permission before sending e-mail is critical because without it, the e-mail is Unsolicited Bulk Email, better known as spam.

There are several common forms of opt-in e-mail:

Unconfirmed opt-in

A new subscriber first gives his/her address to the list software (for instance, on a Web page), but no steps are taken to make sure that this address actually belongs to the person. This can cause e-mail from the mailing list to be considered spam because simple typos of the email address can cause the email to be sent to someone else. Malicious subscriptions are also possible, as are subscriptions that are due to spammers forging email addresses that are sent to the e-mail address used to subscribe to the mailing list.

Confirmed opt-in (COI)

A new subscriber asks to be subscribed to the mailing list, but unlike unconfirmed opt-in, a confirmation e-mail is sent to verify it was really them. Many believe the person must not be added to the mailing list unless an explicit step is taken, such as clicking a special web link or sending back a reply e-mail. This ensures that no person can subscribe someone else out of malice or error. Mail system administrators and non-spam mailing list operators refer to this as confirmed subscription or closed-loop opt-in.

Some marketers call closed loop opt-in "double opt-in."

The term double opt-in was coined by marketers in the late 90s to differentiate it from what they call single opt-in, where a new subscriber to an e-mail list gets a confirmation e-mail telling them they will begin to receive e-mails if they take no action. This is compared to double opt-in where the new subscriber must respond to the confirmation e-mail to be added to the list.

Some marketers contend that double opt-in is like asking for permission twice and that it constitutes unnecessary interference with someone who has already said they want to hear from the marketer.

The term double opt-in has also been co-opted by spammers, diluting its value.

Opt-out

Instead of giving people the option to be put in the list, they are automatically put in and have the option to be taken out.

E-mail Authentication

E-mail authentication is a technique for validating that a person claiming to possess a particular email address actually does so. This is normally done by sending an email containing a token to the address, and requiring that the party being authenticated supply that token before the authentication proceeds. The email containing the token is usually worded so as to explain the situation to the recipient and discourage them from supplying the nonce (often via visiting a URL) unless they in fact were attempting to authenticate.

For example, suppose that one party, Alice, operates a website on which visitors can make accounts to participate or gain access to content. Another party, Bob, comes to that website and creates an account. Bob supplies an email address at which he can be contacted, but Alice does not yet know that Bob is being truthful (consciously or not) about the address. Alice sends a token to Bob's email address for an authentication request, asking Bob to click on a particular URL if and only if the recipient of the mail was making an account on Alice's website. Bob receives the mail and clicks the URL, demonstrating to Alice that he controls the email address he claimed to have. If instead a hostile party, Chuck, were to visit Alice's website attempting to masquerade as Bob, he would be unable to complete the account registration process because the confirmation would be sent to Bob's email address, to which Chuck does not have access.

This degree of email authentication is considered by many anti-spam advocates to be the minimum degree necessary for any opt-in email advertising or other ongoing email communication.

See also

• Closed-loop authentication

Related Books

• Opt In Email List Building by John S. Rhodes
• The Complete Guide to E-mail Marketing by Bruce C. Brown
• E-Mail Marketing For Dummies by John Arnold