POP (Post Office Protocol) and IMAP (Internet Message Access Protocol) are two protocols that allow access to mail folders incoming mail server (not allow sending mail). We can refer to POP with POP3 (latest version) and IMAP with IMAP4. These protocols are supported by most existing mail servers.
Advantages and disadvantages of POP3 vs. IMAP4:
- The number of transactions is low, which is efficient.
- No correlation between the mailing list with the identifiers are used, so each time you connect, you must download the mailing list with your ID (UIDL's).
- Lets work offline, as customer data is downloaded and managed from within the client application.
- You can only manage a single folder.
- The management is simple, it can not mark a message as read on the server, the client is up to that effort.
Advantages and disadvantages of IMAP4 vs. POP3:
- The number of transactions is high, thus requiring greater connectivity between client and server.
- Lets work offline but you must connect to the server for updates in the states of the e-store (if you read an email on the client, indicate on the mail server that is already read with another client that uses the same protocol , will already have read this email and not marked as new)
- You can handle multiple folders (there is only one inbox, but you can move mail to another folder on the server itself).
- Management is more complex, since each action that makes the client must be notified to the server to maintain consistency (if you read mail from a client, other clients should update their status to read, although it depends on the complexity implement the client).
The two protocols provide the basic service for managing email. Keep in mind if you want a distributed system of clients or customers a unified system. For example, if you use multiple email clients like Evolution and Thunderbird, it is interesting to use IMAP4. If instead, you choose to read only the mail using an application such as SaltOS, then POP3 is a good choice, because management is not required on the server unread emails, folders and other benefits it brings as they IMAP4 because SaltOS integrates these benefits in the mail client itself.