PHP uses socket to send emails without the need for SMTP service

Sending mail via socket means sending the above commands to the mail server through the client, so as to realize the SMTP protocol to send mail. PHP uses the socket method to send the mail code as follows :/***

Sending mail via socket means sending the above commands to the mail server through the client, so as to realize the SMTP protocol to send mail. PHP uses the socket method to send the mail code as follows:

/*** SMTP configuration example ** $ config ['smtp _ host'] = smtp server address; * $ config ['smtp _ user'] = SMTP user account; * $ config ['smtp _ pass'] = smtp password; * $ config ['smtp _ port'] = SMTP port; ** @ param string $ from sender's email address * @ param string $ to multiple recipient's email addresses, separated by commas * @ param string $ subject email Title * @ param string $ content email content * @ param array $ config SMTP configuration * @ return boolean */function send_mail ($ from, $ to, $ subject, $ content, $ config) {I F (! $ Fp = fsockopen ($ config ['smtp _ host'], $ config ['smtp _ port'], $ errno, $ errstr, 30) {return FALSE ;} stream_set_blocking ($ fp, TRUE); $ lastmessage = fgets ($ fp, 512); if (substr ($ lastmessage, 0, 3 )! = '000000') {return FALSE;} fputs ($ fp, "EHLO discuz \ r \ n"); $ lastmessage = fgets ($ fp, 220 ); if (substr ($ lastmessage, 0, 3 )! = 220 & substr ($ lastmessage, 0, 3 )! = 250) {return FALSE;} while (1) {if (substr ($ lastmessage, 3, 1 )! = '-' | Empty ($ lastmessage) {break;} $ lastmessage = fgets ($ fp, 512);} fputs ($ fp, "auth login \ r \ n"); $ lastmessage = fgets ($ fp, 512); if (substr ($ lastmessage, 0, 3 )! = 334) {return FALSE;} fputs ($ fp, base64_encode ($ config ['smtp _ user']). & quot; \ r \ n & quot;); $ lastmessage = fgets ($ fp, 512); if (substr ($ lastmessage, 0, 3 )! = 334) {return false;} fputs ($ fp, base64_encode ($ config ['smtp _ pass']). & quot; \ r \ n & quot;); $ lastmessage = fgets ($ fp, 512); if (substr ($ lastmessage, 0, 3 )! = 235) {return FALSE;} fputs ($ fp, "mail from: <". preg_replace ("/. * \ <(. + ?) \>. */"," \ 1 ", $ from ). "> \ r \ n"); $ lastmessage = fgets ($ fp, 512); if (substr ($ lastmessage, 0, 3 )! = 250) {fputs ($ fp, "mail from: <". preg_replace ("/. * \ <(. + ?) \>. */"," \ 1 ", $ from ). "> \ r \ n"); $ lastmessage = fgets ($ fp, 512); if (substr ($ lastmessage, 0, 3 )! = 250) {return FALSE ;}}$ email_tos = array (); foreach (explode (',', $ to) as $ touser) {$ touser = trim ($ touser); if ($ touser) {fputs ($ fp, "rcpt to: <". preg_replace ("/. * \ <(. + ?) \>. */"," \ 1 ", $ touser ). "> \ r \ n"); $ lastmessage = fgets ($ fp, 512); if (substr ($ lastmessage, 0, 3 )! = 250) {fputs ($ fp, "rcpt to: <". preg_replace ("/. * \ <(. + ?) \>. */"," \ 1 ", $ touser ). "> \ r \ n"); $ lastmessage = fgets ($ fp, 512); return FALSE ;}} fputs ($ fp, "DATA \ r \ n "); $ lastmessage = fgets ($ fp, 512); if (substr ($ lastmessage, 0, 3 )! = 354) {return FALSE;} $ maildelimiter = "\ r \ n"; $ subject = '=? '. $ Config ['charset'].'? B? '. Base64_encode (str_replace ("\ r", '', $ subject )).'? = '; $ Content = chunk_split (base64_encode (str_replace ("\ r \ n. "," \ r \ n .. ", str_replace (" \ n "," \ r \ n ", str_replace (" \ r "," \ n ", str_replace (" \ r \ n ", "\ n", str_replace ("\ n \ r", "\ r", $ content); $ from = preg_match ('/^ (. + ?) \ <(. + ?) \> $/', $ From, $ matched )? '=? '. $ Config ['charset'].'? B? '. Base64_encode ($ matched [1]). "? = <$ Matched [2]> ": '=? '. $ Config ['charset'].'? B? '. Base64_encode (str_replace ("\ r", '', $ from )).'? = '; $ Headers = "From: {$ from} {$ maildelimiter} X-Priority: 3 {$ maildelimiter} X-Mailer: Discuz! 2.0 {$ maildelimiter} MIME-Version: 1.0 {$ maildelimiter} Content-type: text/{$ config ['mailtype']}; charset = {$ config ['charset']} {$ maildelimiter} Content-Transfer-Encoding: base64 {$ maildelimiter} "; $ headers. = 'message-ID: <'. date ('ymmdhs '). '. '. substr (md5 ($ content. microtime (), 0, 6 ). rand (100000,999 999 ). '@'. $ _ SERVER ['http _ host']. ">{$ maildelimiter}"; fputs ($ fp, "Date :". date ('r '). "\ r \ n" ); Fputs ($ fp, ":". $. "\ r \ n"); fputs ($ fp, "Subject :". $ subject. "\ r \ n"); fputs ($ fp, $ headers. "\ r \ n"); fputs ($ fp, "\ r \ n"); fputs ($ fp, $ content. "\ r \ n. \ r \ n "); $ lastmessage = fgets ($ fp, 512); if (substr ($ lastmessage, 0, 3 )! = 250) {return FALSE;} fputs ($ fp, "QUIT \ r \ n"); return TRUE ;}