POP

POP , otherwise known as Post office protocol , is a protocol used by the email-clients to retrieve emails from a remote server over a TCP/IP connection.

let us try retrieving mail from my gmail account without using any client ,starting from scratch.

gmail uses POP and IMAP , Let us for the time being concentrate on POP.

wikipedia page on POP gives information which reads

"A POP3 server listens on port 110. Encrypted communication for POP3 is either requested after protocol initiation, using the STLS command, if supported, or by POP3S, which connects to the server using secure sockets layer (SSL) on well-known TCP port 995 (e.g. google Gmail)."

so I need to connect using SSL protocol( this is needed because gmail has SSL security layer protection)

The openssl command does this job . By the way i, need to create a client where i can view the mails . This is also done by passing s_client as argument for this openssl command

$openssl s_client

wait ,dont execute this command in command line, the command is not yet over,
we need to connect it to the gmail POP server ( gmail server that uses POP protocol) , so

$openssl s_client -connect pop.gmail.com:995

we can get the port number detail from wikipedia information i quoted above.

so now ,the task that we have completed so far are

1) client has been created

2) client communictaes using SSL ( this is needed because gmail has SSL security layer protection)

3) We have established connection between the client the POP gmail server

thats all, the rest is what we do in the GUI ....

Just give username , password and then read the mail
So the next thing that we need to type is shown in color

user <type your user name here>

And Another Kind Request :
Chase those fellows standing near by , because the password is exposed as you type.

pass <type your user password here>
STAT
LIST
retr <type the mail number of the mail you wanted to read by seeing the list dispalyed>

after reading the mail ,you can quit and signout using command

quit

Thats all I know about POP .

Bye ,

Harish Kayarohanam