"SMTP" redirects here. For the email delivery company, see SMTP (company). For Short Message Transfer Protocol, see GSM 03.40.
Internet protocol suite
Application layer
BGP
DHCP (v6)
DNS
FTP
HTTP (HTTP/3)
HTTPS
IMAP
IRC
LDAP
MGCP
MQTT
NNTP
NTP
OSPF
POP
PTP
ONC/RPC
RTP
RTSP
RIP
SIP
SMTP
SNMP
SSH
Telnet
TLS/SSL
XMPP
more...
Transport layer
TCP
UDP
DCCP
SCTP
RSVP
QUIC
more...
Internet layer
IP
v4
v6
ICMP (v6)
NDP
ECN
IGMP
IPsec
more...
Link layer
ARP
Tunnels
PPP
MAC
more...
v
t
e
The Simple Mail Transfer Protocol (SMTP) is an Internet standard communication protocol for electronic mail transmission. Mail servers and other message transfer agents use SMTP to send and receive mail messages. User-level email 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 per RFC 8314. For retrieving messages, IMAP (which replaced the older POP3) is standard, but proprietary servers also often implement proprietary protocols, e.g., Exchange ActiveSync.
SMTP's origins began in 1980, building on concepts implemented on the ARPANET since 1971. It has been updated, modified and extended multiple times. The protocol version in common use today has extensible structure with various extensions for authentication, encryption, binary data transfer, and internationalized email addresses. SMTP servers commonly use the Transmission Control Protocol on port number 25 (for plaintext) and 587 (for encrypted communications).
and 28 Related for: Simple Mail Transfer Protocol information
The SimpleMailTransferProtocol (SMTP) is an Internet standard communication protocol for electronic mail transmission. Mail servers and other message...
became the world's largest selling email system. The SimpleMailTransferProtocol (SMTP) protocol was implemented on the ARPANET in 1983. LAN email systems...
application layer protocols, most often Hypertext TransferProtocol (HTTP), although some legacy systems communicate over SimpleMailTransferProtocol (SMTP),...
connected to local networks. The resulting protocol was NNTP, which resembled the SimpleMailTransferProtocol (SMTP) but was tailored for exchanging newsgroup...
transmission of electronic mail from the author's computer and between mail hosts in the Internet uses the SimpleMailTransferProtocol (SMTP), defined in RFC 5321...
is a text-based protocol, incorporating many elements of the Hypertext TransferProtocol (HTTP) and the SimpleMailTransferProtocol (SMTP). A call established...
became the world's largest selling email system. The SimpleMailTransferProtocol (SMTP) protocol was implemented on the ARPANET in 1983. LAN email systems...
the following basic set: SimpleMailTransferProtocol (SMTP) specifies the protocol (RFC 5321, see below) by which e-mail is transmitted RFC 5322 specifies...
hostnames are allowed by some protocols, including HTTP, but disallowed by others, such as the SimpleMailTransferProtocol (SMTP). Mockapetris, Paul. Domain...
Trivial File TransferProtocol (TFTP) is a simple lockstep File TransferProtocol which allows a client to get a file from or put a file onto a remote...
Internet Message Access Protocol (IMAP) is an Internet standard protocol used by email clients to retrieve email messages from a mail server over a TCP/IP...
This is a list of SimpleMailTransferProtocol (SMTP) response status codes. Status codes are issued by a server in response to a client's request made...
Authentication, often abbreviated SMTP AUTH, is an extension of the SimpleMailTransferProtocol (SMTP) whereby a client may log in using any authentication...
format. Historically, all mailtransfer agents (MTAs) added their host name to the reverse path. In the SimpleMailTransferProtocol (SMTP) this reverse path...
cooperates with a mailtransfer agent (MTA) for delivery of the mail. It uses ESMTP, a variant of the SimpleMailTransferProtocol (SMTP), as specified...
facility that supports many kinds of mail-transfer and delivery methods, including the SimpleMailTransferProtocol (SMTP) used for email transport over...
running on the internet protocol suite and using Internet protocols such as FTP, TCP/IP, HTML, and SimpleMailTransferProtocol (SMTP). Intranets are generally...
are those used by Hyper Text TransferProtocol (HTTP), File TransferProtocol (FTP), and SimpleMailTransferProtocol (SMTP); ports 80, 21, and 25 respectively...
by implementing SimpleMailTransferProtocol (SMTP) and possibly providing access to messages through Internet Message Access Protocol (IMAP), the Post...