Sets permitted methods of authentication for IMAP clients. Supported methods are:
extensions list that is passed to the client in response to
It makes sense to specify the extensions supported by the IMAP backends to which the clients are proxied (if these extensions are related to commands used after the authentication, when nginx transparently proxies a client connection to the backend).
The current list of standardized extensions is published at www.iana.org.
Sets the IMAP commands read buffer size. By default, the buffer size is equal to one memory page. This is either 4K or 8K, depending on a platform.