6.3.7 SUBSCRIBE Command

Arguments: mailbox

Responses: no specific responses for this command

Result:

• OK - subscribe completed
• NO - subscribe failure: can't subscribe to that name
• BAD - command unknown or arguments invalid

The SUBSCRIBE command adds the specified mailbox name to the server's set of "active" or "subscribed" mailboxes as returned by the LIST (SUBSCRIBED) command. This command returns a tagged OK response if the subscription is successful or if the mailbox is already subscribed.

A server MAY validate the mailbox argument to SUBSCRIBE to verify that it exists. However, it SHOULD NOT unilaterally remove an existing mailbox name from the subscription list even if a mailbox by that name no longer exists.

Note: This requirement is because a server site can choose to routinely remove a mailbox with a well-known name (e.g., "system-alerts") after its contents expire, with the intention of recreating it when new contents are appropriate.

Example:

C: A002 SUBSCRIBE #news.comp.mail.mime
S: A002 OK SUBSCRIBE completed

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