Uses TCP port 25. Use direct transfer divided mainly into three phases:
- Handshacking (open connection)
The communication between devices takes place by means of an exchange of messages.
Once the mail server has stored the mail there aredifferent protocols to access data:
POP, allows downloading and authentication. E 'stands forPost Office Protocol
-IMAP, allows for complex functions. E 'stands for MailAccess Protocol
The communication begins with the authentication phase. Username and password is sent followed by a response of OK or-ERR (transaction). At this point there are several basic functions:
-LIST, list all posts with their respective number
-RETR, makes a request for a specific message by number
DELE delete a message given its number
QUIT, closes the session
all messages are contained in the server. It has the ability to divide messages into folders and to maintain state between sessions.
-Image (GIF, JPEG)