請問怎麼用socket程式寫寄信

Question

請問各位前輩，如何用socket、port(25)

寄信給[e-mail]

當我建立連線是要跟google做連線還是??

可以告訴我流程或大概?給指示我一個方便謝謝

Answer 1

Favorite Answer

very simple protocol SMTP protocol see RFC 821 document, RFC is free

1. client (user) connect email server ( 25 port) by TCP

client rival email server

connect

------------------------------->

<------------------------------

server greet( 220) OK

HELLO your email server

---------------------------->

send_OK ( 220)

<-----------------------------

MAIL FROM: your email\n

------------------------------>

<----------------------------

send_OK(250)

RCPT TO: send to whom1

-------------------->

<--------------------

send_OK(250 or 251)

RCPT TO: send to whom2

-------------------->

<--------------------

send_OK(250 or 251)

.

.

no Bcc or cc

DATA ( data mode)

------------------------->

<--------------------------

send_OK

send MIME data

. (leave data mode)

---------------------->

<--------------------

OK

close socket

2. above statement is experience of my coding program.