Sets permitted methods of authentication for POP3 clients. Supported methods are:
- USER/PASS, AUTH PLAIN, AUTH LOGIN
- APOP. In order for this method to work, the password must be stored unencrypted.
- AUTH CRAM-MD5. In order for this method to work, the password must be stored unencrypted.
- AUTH EXTERNAL (1.11.6).
Plain text authentication methods
AUTH LOGIN) are always enabled,
though if the
plain method is not specified,
AUTH PLAIN and
will not be automatically included in pop3_capabilities.
pop3_capabilities TOP USER UIDL;
extensions list that is passed to the client in response to
The authentication methods specified in the pop3_auth directive
(SASL extension) and
are automatically added to this list depending on the
starttls directive value.
It makes sense to specify the extensions supported by the POP3 backends to which the clients are proxied (if these extensions are related to commands used after the authentication, when nginx transparently proxies the client connection to the backend).
The current list of standardized extensions is published at www.iana.org.