Email Services Flashcards
Email services in Linux
Name 4 popular Linux MTA email packages?
postfix, send mail, exim, email
Name 3 Linux MDA mail packages used for local email delivery and filtering
Procmail, sieve, binmail
Name the 3 agent functions of a mail server
MTA, MDA, MUA
What does MTA stand for and what does it do?
Message Transfer Agent, handles incoming and outgoing email
What does MDA stand for and what does it do?
Message Delivery Agent, it handles the local delivery step. Common local delivery agents include procmail, binmail and sieve. Mail delivery agents commonly also handle mail filtering and automatic message replying.
What does MUA stand for?
Message User Agent
What does SMTP stand for?
Simple Mail Transfer Protocol
What are the 3 types of user mailboxes commonly used on linux?
The mbox method (the /var/spool/mail file)
$HOME/mail files
Maildir mailbox directories
Name 3 common MUA’s on Linux
binmail, Evolution, thunderbird
What does POP stand for?
Post Office Protocol
What does IMAP stand for?
Internet Message Access Protocol
Name some basic SMTP Commands
HELO - opening greeting MAIL - identify message sender RCPT - identify message recipients DATA - start of message SEND - sends message to terminal SOML - send or mail SAML - send and mail RSET - reset connection VRFY - Verify username on system EXPN - query for lists and aliases HELP - Request list of commands NOOP - No operation, does nothing QUIT - Stop SMTP session TURN - Reverses the SMTP roles
Describe how you would manually send a basic SMTP message
telnet to mail host on port 25. Issue commands: HELO, MAIL FROM, MAIL TO, DATA, QUIT
For example: telnet mail.mymailhost.com 25 HELO localhost MAIL FROM: ted@localhost RCPT TO: frank DATA This is a tests message . QUIT
SMTP response codes are 3 digit codes in reply to command. The first digits denote the category of the response, these can be 50x, 21x, 22x, 25x, 45x, 55x. What categories of response codes are each of these?
50x Error 21x Information 22x Service 25x Action 45x Action 55x Action
What is ESMTP?
Extended SMTP it adds extra commands and features to SMTP, ESMTP sessions are initiated with EHLO instead of the HELO greeting.
What are the 3 types of authentiction used the the POP protocol?
USER/PASS - plain text (bad idea nowadays)
APOP - username in plain text, MD5 hashed password
AUTH - negotiates secure auth between client and server
Name some POP3 client commands
STAT - mailbox status LIST - list messages RETR - return a specific message DELE - delete a message UIDL - provides UID for each message TOP - lists most recent mesages NOOP - no operation, does nothing RSET - Resets the session QUIT - terminates the session
What are the two authentication methods available in IMAP?
LOGIN - Allows the client to use plain text usernames and passwords.
AUTHENTICATE - the client and server negotiate a common encrypted method.
Name some of the IMAP Client Commands
There are many, not expected to remember all…
APPEND - Append a message
CAPABILITY - list imap servers capabilities
CHECK - create a checkpoint
CLOSE - Close the mailbox
COPY - copy a message between mailboxes
CREATE - creates a new mailbox
DELETE - Deletes a mailbox
EXAMINE - open mailbox in read-only
EXPUNGE - delete messages flagged for deletion
FETCH - Retrieve specified message
LIST - Lists all mailboxes
LOGOUT - Logout from the IMAP server
LSUB - list active mailboxes
NOOP - No operation, does nothing
RENAME - renames a mailbox
SEARCH - search messages for a string
SELECT - select a mailbox
STATUS - returns mailbox status
STORE - alter information associated with a message
SUBSCRIBE - adds mailbox to the list of active mailboxes
UID - set message references to UID (instead of seq. no)
UNSUBSCRIBE - removes mailbox from the list of active mailboxes
