cURL supports sending data to an SMTP server
cURL, in combination with command-line options, sends an email to a recipient. Originally the name stood for “see URL” and was later reinterpreted to the current Backronym cURL.
The basic command for sending an email using cURL.
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curl smtp://mail.server.com --mail-from sender@domain.com --mail-rcpt receiver@domain.com --upload-file email.txt |
Example application of cURL SMTP in the terminal emulator:
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curl -v smtp://mail.server.com/email.com --mail-from don@email.com --mail-rcpt rosa@email.com --upload-file email.txt |
The following is the output in the terminal:
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% Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 0 --:-- --:--:-- --:--:-- 0* Trying 10.12.15.13... * TCP_NODELAY set * Connected to mail.server.com (10.12.15.13) port 25 (#0) < 220 mail.server.com ESMTP >EHLO email.com < 250-mail.server.com < 250-PIPELINING < 250-SIZE 22000000 < 250-ETRN < 250-ENHANCEDSTATUSCODES < 250-8BITMIME < 250 DSN 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0> MAIL FROM:<don@email.com> SIZE=355 < 250 2.1.0 Ok >RCPT TO:<rosa@email.com> < 250 2.1.5 Ok > DATA < 354 End data with </rosa@email.com></don@email.com> <CR><LF>.<CR><LF> }[355 bytes data] * We are completely uploaded and fine< 250 2.0.0 Ok: queued as B744B28008 100 355 0 0 100 355 0 355 0:00:01 --:--:-- 0:00:01 1334 * Connection #0 to host mail.server.com left intact |
The -v parameter generates the verbose output.
The file email.txt is uploaded and sent by cURL to the SMTP relay.
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From: Don <don@email.com> To: Rosa <rosa@email.com> Subject: This is an example with cURL SMTP Date: Sam, Jan 19, 2019 12:50:16 PM Hello Rosa, Welcome to cURL email, today is a beautiful day.</rosa@email.com> </don@email.com> |
The contents of email.txt, the From, To, Subject, and Date lines are data fields that serve the Simple Mail Transfer Protocol.
The Mail Transfer Agent (MTA) must be configured to accept mail from the host that uses cURL on it, if it is not an MTA itself, a directive must be configured with smtpd_sender_restrictions, e.g. smtpd_client_restrictions.
