smtp — Simple Mail
Transfer Protocol client
smtp |
[-Chnv] [-a
authfile] [-F
from] [-H
helo] [-s
server] [-T
params] [recipient ...] |
The smtp utility is a Simple Mail Transfer
Protocol (SMTP) client which can be used to run an SMTP transaction against
an SMTP server.
By default, smtp reads the mail content
from the standard input, establishes an SMTP session, and runs an SMTP
transaction for all the specified recipients. The content is sent unaltered
as mail data.
The options are as follows:
-a
authfile- Perform a login before sending the message. The username and password are
read from authfile and need to be on the first and
second line respectively. This option requires a TLS or STARTTLS
server.
-C- Do not require server certificate to be valid. This flag is deprecated.
Use “
-T
noverify” instead.
-F
from- Set the return-path (MAIL FROM) for the SMTP transaction. Default to the
current username.
-H
helo- Define the hostname to advertise (HELO) when establishing the SMTP
session.
-h- Display usage.
-n- Do not actually execute a transaction, just try to establish an SMTP
session and quit. When this option is given, no message is read from the
standard input.
-s
server- Specify the server to connect to and connection parameters. The format is
[proto://[user:pass@]]host[:port].
The following protocols are available:
- smtp
- Normal SMTP session with opportunistic STARTTLS.
- smtp+tls
- Normal SMTP session with mandatory STARTTLS.
- smtp+notls
- Plain text SMTP session without TLS.
- lmtp
- LMTP session with opportunistic STARTTLS.
- lmtp+tls
- LMTP session with mandatory STARTTLS.
- lmtp+notls
- Plain text LMTP session without TLS.
- smtps
- SMTP session with forced TLS on connection.
Defaults to “smtp://localhost:25”.
-T
params- Set specific parameters for TLS sessions. The params
string is a comma or space separated list of options. The available
options are:
cafile=filename- Use filename as root certificates file instead
of the system default.
ciphers=value- Specify the allowed ciphers. Refer to
tls_config_set_ciphers(3) for
value.
nosni- Disable Server Name Indication (SNI).
noverify- Do not require server certificate to be valid.
protocols=value- Specify the protocols to use. Refer to
tls_config_parse_protocols(3) for
value.
servername=value- Use value for Server Name Indication (SNI).
Defaults to the specified server hostname.
-v- Be more verbose. This option can be specified multiple times.
The smtp program first appeared in
OpenBSD 6.4.