tcp is more reliable than udp,udp may have failures or data loss, so we can't afford to have losses in http,smtp,pop3 and so on.Accurate data is very important is all this protocols
ImprovementThe above answer being true, it is worth mentioning that none of the Protocols in your question actually require TCP as its Transport protocol. They simply require the use of a reliable protocol at the Transport Layer (refer ISO::OSI network model) and TCP is the best there is right now.And also, since these protocols were developed after the reign of TCP as the primary transport protocol started, integrating them with TCP is relatively easier. If used with other protocols, it has to be explicitly configured into the App protocols.
Regards
Binaek Sarkar
Foundation
http://www.foundation.net.in/
These protocols require guaranteed reliable delivery, so they must use TCP. If they didn't care about the quality of the transmission they could use UDP, but in this case it is important to verify that all the data arrived correctly and safely.
In the Incoming mail (POP3, IMAP, or HTTP) server box, type pop3.live.com. In the Outgoing mail (SMTP) server box, type smtp.live.co
Hotmail does not support pop3 unless you are a paying subscriber. GMX.com is free mail that does support pop3 and imap.
SMTP (simple transfer mail protocol) which is used as the outgoing mail server and it uses port number :25 POP3 (Post Office Protocol 3) is the most recent version of a standard protocol for receiving e-mail. POP3 is a client/server protocol in which e-mail is received and held for you by your Internet server and it uses port 110
FTP; HTTP; DNS (uses both TCP and UDP); several e-mail protocols including POP3, SMTP, IMAP4.
Port number of SMTP is 25 and of IMAP is 143. (These are the standard port numbers used)
POP3 is actually Post Office Protocol 3 which is an enhanced version of the standard protocol for receiving email. POP3 is a client/server protocol in which the email can be received. There are other protocols such as Internet Message Access Protocol(IMAP) Simple Mail Transfer Protocol (SMTP). if this answer is wrong,correct me..
POP3 is one of two e-mail inbox protocols (POP3: Post Office Protocol version 3; IMAP: Internet Message Access Protocol). SMTP (Simple Mail Transfer Protocol) is used in conjunction with either POP3 or IMAP to allow users to send e-mail addresses as well as receive them. Most web-based e-mail services does this transparently behind their networks and present a fancy UI for users to access their e-mail inboxes. However, you can opt to enable IMAP/POP3 + SMTP if you wish to not have to open up a Web browser every time you want to look at your e-mails, and use a dedicated e-mail program instead (i.e. Microsoft Outlook or Mozilla Thunderbird)
SMTP (Simple Mail Transfer Protocol) - sends mail only POP (Post Office Protocol) - retrieves mail and manages mailboxes IMAP (Internet Message Access Protocol) - retrieves mail and manages mailboxes
Call your Internet provider, you need to get this information from them.
SMTP - 25, 465, and 587 POP - 109, 110, and 995 IMAP - 143, 220, and 993
Automation file synchronization over LAN and WAN, FTP, HTTP, SMTP, POP3, PING. File
Most email clients use one of three protocols to receive an email message. They are SMTP (Simple Mail Transfer Protocol), POP (Post Office Protocol), or IMAP (Internet Message Access Protocol).