SMTP uses TCP, not UDP.
No it uses UDP packets.
tftp snmp nfs
UDP: DNS, TFTP, DHCP... TCP: SMTP, HTTP, HTTPS, DNS, FTP, SHH, Telnet...
the u in udp stands for unreliable and since email is important it is sent using tcp through say smtp or pop3
SMTP is simple mail transport protocol. SNMP is simple network management protocol that is UDP based.
DNS uses both TCP and UDP, also a lot of online chats use UDP. I think even when you want videos on YouTube UDP is used to deliver video and audio.
TCP and UDP are two different layer 4 protocols. TCP reliably sends data with acknowledgments and UDP sends data without checking if the destination received it. Skype uses UDP while email uses TCP.
RIP uses UDP protocol with port number 520
TFTP uses UDP - TFTP stands for Trivial FTP, and it is called trivial because it does not check to ensure delivery, it uses UDP which makes a best-effort delivery attempt
SMTP was designed to send email between computers in network. And uses TCP for reliability.
DNS does.