clients typically use SMTP only for sending messages to a mail server for relaying, and typically submit outgoing email to the mail server on port 587 or 465...

An open mail relay is a Simple Mail Transfer Protocol (SMTP) server configured in such a way that it allows anyone on the Internet to send e-mail through...

authentication mechanism supported by the server. It is mainly used by submission servers, where authentication is mandatory. SMTP as specified by Jon Postel in the...

Transfer Protocol (SMTP) response status codes. Status codes are issued by a server in response to a client's request made to the server. Unless otherwise...

single DHCP server may service the entire network when aided by DHCP relay agents located on the interconnecting routers. Such agents relay messages between...

On-Demand Mail Relay (ODMR) is an SMTP extension standardized in RFC 2645 that allows e-mail to be relayed to the recipients after they have been authenticated...

The Courier Mail Server is a mail transfer agent (MTA) server that provides SMTP, IMAP, POP3, SMAP, webmail, and mailing list services with individual...

Simple Mail Transfer Protocol (SMTP). When a recipient mailbox of a message is not hosted locally, the message is relayed, that is, forwarded to another...

non-proxied protocol such as SMTP (port 25). By attempting to make a connection to an IP address at which there is known to be no server. The proxy will accept...

and server through a proxy server. SOCKS5 optionally provides authentication so only authorized users may access a server. Practically, a SOCKS server proxies...

"integrated" access to SMTP-based networks for the first time. Unlike Microsoft Mail (which required a standalone SMTP relay), Exchange Server 5.0 could, with...

Relay Chat is implemented as an application layer protocol to facilitate communication in the form of text. The chat process works on a client–server...

Email may also be a push system: SMTP is a push protocol (see Push e-mail). However, the last step—from mail server to desktop computer—typically uses...

Hypertext Transfer Protocol (HTTP) and the Simple Mail Transfer Protocol (SMTP). A call established with SIP may consist of multiple media streams, but...

the Echo Protocol for relaying ICMP datagrams (or port 9 for the Discard Protocol) is also configured by default as a proxy to relay Wake-on-LAN (WOL) magic...

message transfer agent (MTA) server run by the recipient's ISP. smtp.a.org sends the message to mx.b.org using SMTP. This server may need to forward the message...

procedures. x4z – Not defined. x5z – File system. These replies relay status codes from the server file system. The third digit of the reply code is used to...

for start of authority (SOA), IP addresses (A and AAAA), SMTP mail exchangers (MX), name servers (NS), pointers for reverse DNS lookups (PTR), and domain...

those servers are offline. At this point, using any *.dsbl.org lookups in an RBL check results in DNS failures and can even prevent an SMTP server from...

administrators enable them, leaving the receiving SMTP server no effective way to validate the sender's email address. SMTP proxies allow combating spam in real time...

by the SMTP-based Internet e-mail. Despite this, it has been widely used within organizations and was a core part of Microsoft Exchange Server until 2006;...

POP before SMTP or SMTP after POP is a method of authentication used by mail server software which helps allow users the option to send e-mail from any...

Transfer Protocol (SMTP), a client–server model; clients do not talk directly to one another as it is decentralized - anyone can run a server. By design, there...

Simple Mail Transfer Protocol (SMTP) implementation for testing spam capability. Bringing down the Mega-D's SMTP server disables the entire pool of bots...

(MUA) knows the outgoing mail SMTP server from its configuration. An MTA (or a relay server) typically determines which server to connect to by looking up...

down. Quoting from the RFC: Any system that includes an SMTP server supporting mail relaying or delivery MUST support the reserved mailbox "postmaster"...

Transfer – ask a DNS server for all it knows about a domain SMTP Relay Check – check whether a mail server allows third party relaying Scan Addresses – scan...

without a rejecting MTA, or as RFC 5321 puts it: "If an SMTP server has accepted the task of relaying the mail and later finds that the destination is incorrect...

the initial SMTP connection, mailservers can do a range of checks, and often reject email with a 5xx error code while the sending server is still connected...

an access server authentication and accounting protocol. It was later brought into IEEE 802 and IETF standards. RADIUS is a client/server protocol that...