Module ngx_mail_core_module
Example Configuration Directives listen max_errors protocol resolver resolver_timeout server server_name timeout |
This module is not built by default, it should be
enabled with
the --with-mail
configuration parameter.
Example Configuration
worker_processes auto; error_log /var/log/nginx/error.log info; events { worker_connections 1024; } mail { server_name mail.example.com; auth_http localhost:9000/cgi-bin/nginxauth.cgi; imap_capabilities IMAP4rev1 UIDPLUS IDLE LITERAL+ QUOTA; pop3_auth plain apop cram-md5; pop3_capabilities LAST TOP USER PIPELINING UIDL; smtp_auth login plain cram-md5; smtp_capabilities "SIZE 10485760" ENHANCEDSTATUSCODES 8BITMIME DSN; xclient off; server { listen 25; protocol smtp; } server { listen 110; protocol pop3; proxy_pass_error_message on; } server { listen 143; protocol imap; } server { listen 587; protocol smtp; } }
Directives
Syntax: |
listen
|
---|---|
Default: | — |
Context: |
server |
Sets the address
and port
for the socket
on which the server will accept requests.
It is possible to specify just the port.
The address can also be a hostname, for example:
listen 127.0.0.1:110; listen *:110; listen 110; # same as *:110 listen localhost:110;
IPv6 addresses (0.7.58) are specified in square brackets:
listen [::1]:110; listen [::]:110;
UNIX-domain sockets (1.3.5) are specified with the “unix:
”
prefix:
listen unix:/var/run/nginx.sock;
Different servers must listen on different
address
:port
pairs.
The ssl
parameter allows specifying that all
connections accepted on this port should work in SSL mode.
The proxy_protocol
parameter (1.19.8)
allows specifying that all connections accepted on this port should use the
PROXY
protocol.
Obtained information is passed to the
authentication server
and can be used to
change the client address.
The listen
directive
can have several additional parameters specific to socket-related system calls.
-
backlog
=number
-
sets the
backlog
parameter in thelisten()
call that limits the maximum length for the queue of pending connections (1.9.2). By default,backlog
is set to -1 on FreeBSD, DragonFly BSD, and macOS, and to 511 on other platforms. -
rcvbuf
=size
-
sets the receive buffer size
(the
SO_RCVBUF
option) for the listening socket (1.11.13). -
sndbuf
=size
-
sets the send buffer size
(the
SO_SNDBUF
option) for the listening socket (1.11.13). -
bind
-
this parameter instructs to make a separate
bind()
call for a given address:port pair. The fact is that if there are severallisten
directives with the same port but different addresses, and one of thelisten
directives listens on all addresses for the given port (*:
port
), nginx willbind()
only to*:
port
. It should be noted that thegetsockname()
system call will be made in this case to determine the address that accepted the connection. If thebacklog
,rcvbuf
,sndbuf
,ipv6only
, orso_keepalive
parameters are used then for a givenaddress
:port
pair a separatebind()
call will always be made. -
ipv6only
=on
|off
-
this parameter determines
(via the
IPV6_V6ONLY
socket option) whether an IPv6 socket listening on a wildcard address[::]
will accept only IPv6 connections or both IPv6 and IPv4 connections. This parameter is turned on by default. It can only be set once on start. -
so_keepalive
=on
|off
|[keepidle
]:[keepintvl
]:[keepcnt
] -
this parameter configures the “TCP keepalive” behavior
for the listening socket.
If this parameter is omitted then the operating system’s settings will be
in effect for the socket.
If it is set to the value “
on
”, theSO_KEEPALIVE
option is turned on for the socket. If it is set to the value “off
”, theSO_KEEPALIVE
option is turned off for the socket. Some operating systems support setting of TCP keepalive parameters on a per-socket basis using theTCP_KEEPIDLE
,TCP_KEEPINTVL
, andTCP_KEEPCNT
socket options. On such systems (currently, Linux 2.4+, NetBSD 5+, and FreeBSD 9.0-STABLE), they can be configured using thekeepidle
,keepintvl
, andkeepcnt
parameters. One or two parameters may be omitted, in which case the system default setting for the corresponding socket option will be in effect. For example,
will set the idle timeout (so_keepalive=30m::10
TCP_KEEPIDLE
) to 30 minutes, leave the probe interval (TCP_KEEPINTVL
) at its system default, and set the probes count (TCP_KEEPCNT
) to 10 probes.
Syntax: |
mail { ... } |
---|---|
Default: | — |
Context: |
main |
Provides the configuration file context in which the mail server directives are specified.
Syntax: |
max_errors |
---|---|
Default: |
max_errors 5; |
Context: |
mail , server |
This directive appeared in version 1.21.0.
Sets the number of protocol errors after which the connection is closed.
Syntax: |
protocol
|
---|---|
Default: | — |
Context: |
server |
Sets the protocol for a proxied server. Supported protocols are IMAP, POP3, and SMTP.
If the directive is not set, the protocol can be detected automatically based on the well-known port specified in the listen directive:
-
imap
: 143, 993 -
pop3
: 110, 995 -
smtp
: 25, 587, 465
Unnecessary protocols can be disabled using the
configuration
parameters --without-mail_imap_module
,
--without-mail_pop3_module
, and
--without-mail_smtp_module
.
Syntax: |
resolver
resolver |
---|---|
Default: |
resolver off; |
Context: |
mail , server |
Configures name servers used to find the client’s hostname to pass it to the authentication server, and in the XCLIENT command when proxying SMTP. For example:
resolver 127.0.0.1 [::1]:5353;
The address can be specified as a domain name or IP address, with an optional port (1.3.1, 1.2.2). If port is not specified, the port 53 is used. Name servers are queried in a round-robin fashion.
Before version 1.1.7, only a single name server could be configured. Specifying name servers using IPv6 addresses is supported starting from versions 1.3.1 and 1.2.2.
By default, nginx will look up both IPv4 and IPv6 addresses while resolving.
If looking up of IPv4 or IPv6 addresses is not desired,
the ipv4=off
(1.23.1) or
the ipv6=off
parameter can be specified.
Resolving of names into IPv6 addresses is supported starting from version 1.5.8.
By default, nginx caches answers using the TTL value of a response.
An optional valid
parameter allows overriding it:
resolver 127.0.0.1 [::1]:5353 valid=30s;
Before version 1.1.9, tuning of caching time was not possible, and nginx always cached answers for the duration of 5 minutes.
To prevent DNS spoofing, it is recommended configuring DNS servers in a properly secured trusted local network.
The optional status_zone
parameter (1.17.1)
enables
collection
of DNS server statistics of requests and responses
in the specified zone
.
The parameter is available as part of our
commercial subscription.
The special value off
disables resolving.
Syntax: |
resolver_timeout |
---|---|
Default: |
resolver_timeout 30s; |
Context: |
mail , server |
Sets a timeout for DNS operations, for example:
resolver_timeout 5s;
Syntax: |
server { ... } |
---|---|
Default: | — |
Context: |
mail |
Sets the configuration for a server.
Syntax: |
server_name |
---|---|
Default: |
server_name hostname; |
Context: |
mail , server |
Sets the server name that is used:
- in the initial POP3/SMTP server greeting;
- in the salt during the SASL CRAM-MD5 authentication;
-
in the
EHLO
command when connecting to the SMTP backend, if the passing of the XCLIENT command is enabled.
If the directive is not specified, the machine’s hostname is used.
Syntax: |
timeout |
---|---|
Default: |
timeout 60s; |
Context: |
mail , server |
Sets the timeout that is used before proxying to the backend starts.