O

Opt-in: The people subscribed to a mailing list have asked to receive the information or advertising. (Double Op-In means the person requesting information must confirm their desire to receive it by responding to an email message after subscribing.)

Opt-out: The people subscribed to a mailing list have not asked to receive the email (it's SPAM), but they have the option of removing their name from the list if they wish. Removing your name from an Opt-Out list often has the undesirable effect of getting your name and email address on even more lists!

.org: A suffix indicating a non-profit organization domain.