=encoding utf-8

=head1 NAME

ngx_mail_pop3_module - Module ngx_mail_pop3_module




=head1 Directives

=head2 pop3_auth


B<syntax:> pop3_auth I<I<C<method>> ...>


B<default:> I<plain>


B<context:> I<mail>


B<context:> I<server>





Sets permitted methods of authentication for POP3 clients.
Supported methods are:

=over



=item C<plain>




L<USERE<sol>PASS|https://datatracker.ietf.org/doc/html/rfc1939>,
L<AUTH PLAIN|https://datatracker.ietf.org/doc/html/rfc4616>,
L<AUTH LOGIN|https://datatracker.ietf.org/doc/html/draft-murchison-sasl-login-00>



=item C<apop>




L<APOP|https://datatracker.ietf.org/doc/html/rfc1939>.
In order for this method to work, the password must be stored unencrypted.



=item C<cram-md5>




L<AUTH CRAM-MD5|https://datatracker.ietf.org/doc/html/rfc2195>.
In order for this method to work, the password must be stored unencrypted.



=item C<external>




L<AUTH EXTERNAL|https://datatracker.ietf.org/doc/html/rfc4422> (1.11.6).




=back







Plain text authentication methods
(C<USERE<sol>PASS>, C<AUTH PLAIN>,
and C<AUTH LOGIN>) are always enabled,
though if the C<plain> method is not specified,
C<AUTH PLAIN> and C<AUTH LOGIN>
will not be automatically included in L</pop3_capabilities>.







=head2 pop3_capabilities


B<syntax:> pop3_capabilities I<I<C<extension>> ...>


B<default:> I<TOP USER UIDL>


B<context:> I<mail>


B<context:> I<server>





Sets the
L<POP3 protocol|https://datatracker.ietf.org/doc/html/rfc2449>
extensions list that is passed to the client in response to
the C<CAPA> command.
The authentication methods specified in the L</pop3_auth> directive
(L<SASL|https://datatracker.ietf.org/doc/html/rfc2449> extension) and
L<STLS|https://datatracker.ietf.org/doc/html/rfc2595>
are automatically added to this list depending on the
L<ngx_mail_ssl_module> 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
L<www.iana.org|http://www.iana.org/assignments/pop3-extension-mechanism>.