SMTP(1) General Commands Manual SMTP(1) (NAME) smtp - Simple Mail Transfer Protocol (SYNOPSIS) smtp [-Chnv] [-a authfile] [-F from] [-H helo] [-s server] [-T params] [recipient ...] (DESCRIPTION) smtp Simple Mail Transfer Protocol (SMTP) SMTP SMTP . smtp SMTP SMTP . . : -a authfile . authfile . server TLS STARTTLS . -C . . "-T noverify" . -F from (MAIL FROM) SMTP. . -H helo (hostname) (HELO) SMTP. -h . -n SMTP . . -s server . : [proto://[user:pass@]]host[:port]. : smtp SMTP STARTTLS (opportunistic). smtp+tls SMTP STARTTLS . smtp+notls (plain text) SMTP TLS. lmtp LMTP STARTTLS (opportunistic). lmtp+tls LMTP STARTTLS . lmtp+notls (plain text) LMTP TLS. smtps SMTP TLS . "smtp://localhost:25" . -T params TLS. params . : cafile=filename filename . ciphers=value (ciphers) . value tls_config_set_ciphers(3) . nosni Server Name Indication (SNI). noverify . protocols=value . value tls_config_parse_protocols(3) . servername=value value Server Name Indication (SNI). . -v ( ). . (SEE ALSO) smtpd(8) (HISTORY) smtp OpenBSD 6.4 . Linux 6.12.113+deb13-amd64 May 23, 2021 Linux 6.12.113+deb13-amd64