{"id":40,"date":"2008-07-31T08:00:31","date_gmt":"2008-07-31T15:00:31","guid":{"rendered":"http:\/\/cknotes.com\/?p=40"},"modified":"2008-07-31T08:00:31","modified_gmt":"2008-07-31T15:00:31","slug":"smtp-protocol-in-a-nutshell","status":"publish","type":"post","link":"https:\/\/cknotes.com\/smtp-protocol-in-a-nutshell\/","title":{"rendered":"SMTP Protocol (in a Nutshell)"},"content":{"rendered":"

Question:<\/strong><\/p>\n

SendMime requires a from \u00a0and \u00a0recipients address string, but the MIME message contains both .\u00a0 The message I receive from the SendMime seems to ignore the addresses in the call and uses the one in the MIME.\u00a0 So why require a from and recipient address?<\/p>\n

Answer:<\/strong><\/p>\n

The SMTP protocol works like this:<\/p>\n

1) A client connects to an SMTP server.<\/p>\n

2) The SMTP server says “hello”<\/p>\n

3) The client authenticates (if necessary) by logging in.<\/p>\n

4) Now it’s time to send an email.\u00a0 First, the client sends a “MAIL FROM” command with the email address that is the reverse-path.\u00a0 This is the email address that would receive a bounce or delivery status notification.<\/p>\n

5) The client then sends one or more “RCPT TO” commands, each with a recipient email address.\u00a0 It doesn’t matter if the recipient is a “To” , “CC”, or “BCC”, all recipient email addresses are passed to the SMTP server via “RCPT TO” commands.<\/p>\n

6) Finally, the MIME source of the email is sent with a “DATA” command.\u00a0\u00a0\u00a0 Note: The MIME source has header fields for “From”, “To”, and “CC”.\u00a0 These are the email addresses that will be seen by the receiver of the email.\u00a0 The actual recipients are the email addresses passed via the RCPT TO commands.\u00a0 It’s possible to create an email such that the “To” header field contains “santa.claus@northpole.com”, but you pass actual email addresses in the RCPT TO commands.\u00a0 The person receiving such an email (if not filtered as SPAM) would scratch his\/her head and wonder why he\/she received an email addressed to Santa Claus.<\/p>\n

The Chilkat mailman’s SendMime method has these arguments:\u00a0 From, CommaSeparatedRcptToEmailAddresses, MimeSource.\u00a0\u00a0\u00a0 Given the above explanation, it should be obvious how these arguments are used in sending the email…<\/p>\n","protected":false},"excerpt":{"rendered":"

Question: SendMime requires a from \u00a0and \u00a0recipients address string, but the MIME message contains both .\u00a0 The message I receive from the SendMime seems to ignore the addresses in the call and uses the one in the MIME.\u00a0 So why require a from and recipient address? Answer: The SMTP protocol works like this: 1) A […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[426],"class_list":["post-40","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-smtp"],"_links":{"self":[{"href":"https:\/\/cknotes.com\/wp-json\/wp\/v2\/posts\/40","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cknotes.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cknotes.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cknotes.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/cknotes.com\/wp-json\/wp\/v2\/comments?post=40"}],"version-history":[{"count":0,"href":"https:\/\/cknotes.com\/wp-json\/wp\/v2\/posts\/40\/revisions"}],"wp:attachment":[{"href":"https:\/\/cknotes.com\/wp-json\/wp\/v2\/media?parent=40"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cknotes.com\/wp-json\/wp\/v2\/categories?post=40"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cknotes.com\/wp-json\/wp\/v2\/tags?post=40"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}