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SMTP(1) General Commands Manual SMTP(1)
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.
smtpd(8)
The smtp program first appeared in OpenBSD 6.4.
This page is part of the OpenSMTPD (a FREE implementation of the
server-side SMTP protocol) project. Information about the
project can be found at https://www.opensmtpd.org/. If you have
a bug report for this manual page, see
⟨https://github.com/OpenSMTPD/OpenSMTPD/issues⟩. This page was
obtained from the project's upstream Git repository
⟨https://github.com/OpenSMTPD/OpenSMTPD.git⟩ on 2024-06-14. (At
that time, the date of the most recent commit that was found in
the repository was 2024-06-09.) If you discover any rendering
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GNU May 23, 2021 SMTP(1)