POP3/IMAP Information and Comparison
POP and IMAP are two email protocols commonly used today. While POP continues to be the most popular among single client users, IMAP is also available for users who have multiple computers or who need to access their email from multiple locations.
POP3 (Post Office Protocol)
The POP protocol was originally designed around the offline mail delivery model due to the high costs of having to stay online to retrieve mail. With POP, users connect on to their mail server, download the mail to their local computer, disconnect from the server letting them read the emails while offline. Emails are stored on the server until the user downloads the mail using a mail client such as Microsoft Outlook or Eudora.
POP3 Advantages
  • The POP protocol allows a user to store their email locally. This allows a user which is not connected to the internet, to still access and read downloaded email.
  • POP email is less intensive on the server side. Using POP mail frees up server disk space because it downloads emails and attachments then deletes them from the email server.
  • POP email is multi-system friendly. For many users that have older systems their email clients will most likely not run IMAP mail, therefore POP email will be their only choice.
  • POP3 Disadvantages
  • POP email was designed for use with a single email client on a single computer. Even though there are “leave-mail-on-server” enhancements of new POP servers and clients, when implemented, this feature forces the downloading of the same emails many times which can drain bandwidth, server resources and client disk space.
  • IMAP (Internet Message Access Protocol)
    IMAP was recently developed for users who needed access to their email on the server without having to download the mail to a local machine. Users can manipulate mail and folders on the server side. Folders and mail boxes can also be given shared access for uses such as announcements and common projects.
    WebMail is a great example of the IMAP protocol although it is accessed through the web and not an email client such as Microsoft Outlook or Eudora.
    IMAP Advantages
  • Cross compatibility with multiple email clients. This means that any computer with an IMAP client can view email
  • Since IMAP email still resides on an email server, multiple users can view the same email using public and group folders
  • IMAP email supports many configurations because it is compatible with all email delivery models.
  • IMAP Disadvantages
  • IMAP email resides on the server; this will take away from allotted storage space.
  • With IMAP supporting so many email options, this can often confuse and overwhelm a user.
  • Key Differences
    POP email is designed to be used by one client and one computer where as IMAP is designed to be used by various users using different computers.
    IMAP stores mail on email servers whereas POP stores email on a clients computer
    POP clients have facilities for organizing mail into folders on the clients computer where when using IMAP, folders can be on the server or client side.
    POP sends messages one way, from the server to the client. IMAP can copy and move messages back and forth between mailboxes on multiple accounts as well as between servers and clients.
    POP email only supports one user to access one mailbox. IMAP mail allows users to access multiple public and private folders where users can change the status of message to share for multiple viewing.