Search results
Results from the WOW.Com Content Network
The meaning of the "detail" field depends on the class and the subject, and are listed in RFC 3463 and RFC 5248. A server capable of replying with an Enhanced Status Code MUST preface (prepend) the Text Part of SMTP Server responses with the Enhanced Status Code followed by one or more spaces.
The initiating host, the SMTP client, can be either an end-user's email client, functionally identified as a mail user agent (MUA), or a relay server's mail transfer agent (MTA), that is an SMTP server acting as an SMTP client, in the relevant session, in order to relay mail. Fully capable SMTP servers maintain queues of messages for retrying ...
This class of status code indicates the client must take additional action to complete the request. Many of these status codes are used in URL redirection. [2]A user agent may carry out the additional action with no user interaction only if the method used in the second request is GET or HEAD.
When you get a message from a "MAILER-DAEMON" or a "Mail Delivery Subsystem" with a subject similar to "Failed Delivery," this means that an email you sent was undeliverable and has been bounced back to you. These messages are sent automatically and often include the reason for the delivery failure.
Email clients using IMAP generally leave messages on the server until the user explicitly deletes them. This and other characteristics of IMAP operation allow multiple clients to manage the same mailbox. Most email clients support IMAP in addition to Post Office Protocol (POP) to retrieve messages. [6] IMAP offers access to the mail storage.
To use Unicode in certain email header fields, e.g. subject lines, sender and recipient names, the Unicode text has to be encoded using a MIME "Encoded-Word" with a Unicode encoding as the charset. To use Unicode in the domain part of email addresses, IDNA encoding must traditionally be used.
SMTP proxies often serve as the initial, network-facing layer in an email system, processing SMTP connections from clients before forwarding data to a second layer of mail servers. [3] SMTP proxies often implement the first and/or only layer of defence in an inbound anti-spam filtering system, where they can analyze messages using a spam ...
Because the initial handshake takes place in plain text, an attacker in control of the network can modify the server messages via a man-in-the-middle attack to make it appear that TLS is unavailable (called a STRIPTLS attack). Most SMTP clients will then send the email and possibly passwords in plain text, often with no notification to the user.