What is SMTP?
Is the acronym for Simple Mail Transfer Protocol, which is a protocol for sending e-mail messages between servers. In a nutshell, SMTP is generally used to send messages from a mail client to a mail server. Most email frameworks that send e-mails over the Internet make use of SMTP to send messages from one server to the next. The messages would then be able to be retrieved with an email client either with POP or IMAP. This is the reason you have to indicate both the POP or IMAP server and the SMTP server when you arrange your email application (more info on SMTP Wikipedia page and SMTP explained simply).
What is POP3?
Post Office Protocol version 3 (POP3) is a standard mail protocol used for receiving e-mail from a remote server to a local e-mail client. POP3 enables you to download email messages on your local PC and read them notwithstanding when you are disconnected.
Note that when you use POP3 to connect with your email account, messages are downloaded locally and expelled from the email server. This implies, in the event that you get to access your account from different locations, then POP3 may not be the best alternative for you. but if you use POP3, your messages will be stored on your local PC, which reduces the space your email account uses on your web server.
What is IMAP?
The Internet Message Access Protocol (IMAP) is a mail protocol which is used to access email on a remote web server from a local client. POP3 and IMAP are generally the two most used Internet mail protocols for retrieving e-mails. The two protocols are supported by cutting-edge email clients and web servers.
Although Simple Mail Transfer Protocol (SMTP) is a transfer protocol (TP) used for sending and receiving e-mail and since it is constrained in its capacity to queue messages at the receiving end, it is generally used with one of two different protocols, POP3 or IMAP, which let the client save messages in a server mailbox and download them occasionally from the server. At the end of the day, clients will literally use a program that uses SMTP for sending e-mail and its either POP3 or IMAP for receiving e-mail. On Unix-based frameworks, sendmail is the most used SMTP server for e=mail. A commercial Sendmail package includes a POP3 server. Microsoft Exchange incorporates an SMTP server and likewise, be set up to incorporate POP3 support.
While the POP3 convention accepts that your email is being gotten to just from one application, IMAP permits concurrent access by various customers. This is the reason IMAP is more appropriate for you in case you will access your email from different locations or if your messages are overseen by numerous clients.