SMTP
ProtocolDefinition
Simple Mail Transfer Protocol (SMTP) is the standard protocol for sending email. SMTP servers relay email from sender to recipient's mail server on port 25 (server-to-server), 587 (submission with auth), or 465 (SMTPS). Receiving email uses IMAP or POP3.
Frequently Asked Questions
Related Terms
TCP
Transmission Control Protocol (TCP) is a connection-oriented, reliable transport-layer protocol. TCP guarantees ordered delivery of packets, retransmits lost packets, and provides flow control and congestion control. It is used for HTTP, HTTPS, SSH, SMTP, and most reliable internet communications.
UDP
User Datagram Protocol (UDP) is a connectionless, best-effort transport-layer protocol. UDP sends packets without establishing a connection or guaranteeing delivery, order, or duplicate protection. This makes UDP faster than TCP and suitable for real-time applications.
DNS
The Domain Name System (DNS) is the internet's distributed directory service that translates human-readable domain names (example.com) to IP addresses (93.184.216.34). DNS uses a hierarchical system of servers: root servers → TLD servers → authoritative nameservers.
IP Address
An Internet Protocol (IP) address is a unique numerical label assigned to each device on a network. IP addresses enable routing of data packets across the internet. IPv4 uses 32-bit addresses (e.g., 192.168.1.1); IPv6 uses 128-bit addresses (e.g., 2001:db8::1).