POP3

POP3 is also known as Post Office Protocol 3. 

• It's the most recent version of a standard protocol for receiving email.
• Can be thought of as a 'store-and-forward' service.
• Creates local copies of emails and deletes the originals from the server, once the email is opened. The emails are:
  1. Tied to that specific device.
  2. Cannot be accessed through any webmail, separate clients or other computers.

Port Numbers

For Incoming POP3:

• 110 - Default POP3 non-encrypted port.
• 995 - This is the port you need to use if you want to connect using POP3 securely.

Some implementations allow users or an administrator to specify that mail be
saved for a certain period of time.

IMAP

IMAP is also known as Internet Message Access Protocol.

• Standard protocol for receiving email.
• Can be thought of as a remote file server.
• Provides the user with more capabilities for:
  1. Organising emails in folders on the server.
  2. Retaining emails on the server. Emails are stored until the user deletes them.
• Allows users to view the same emails from different email clients or webmail
  interfaces.

Port Numbers

For Incoming IMAP:

• 143 - The default IMAP non-encrypted port.
• 993 & 465 - If you want to connect using IMAP securely, use this port.

The Differences between POP3 and IMAP

Your emails exist within an email server. POP3 and IMAP are two standard protocols that allow you to manage the emails on your server via an email client such as Apple Mail or Outlook.

The IMAP protocol synchronises emails on your computer and account within an email server where your emails reside. Example: if you chose to delete an email using IMAP protocol, it will also delete it from the email server.

The POP3 protocol simply downloads the emails within your account on an email server to your email client’s inbox.

SMTP

SMTP is also known as Simple Mail Transfer Protocol. It's a protocol for transferring email across the internet.

Outgoing for SMTP

• 25 - Default SMTP non-encrypted port.
• 587 - If you want to send messages using SMTP securely, use this port.
• 2525 - This port is opened on all SiteGround servers in case port 25 is filtered (by your ISP for example) and you want to send non-encrypted emails with SMTP.

Process

• The email is sent with SMTP.
• A mail handler receives it on the recipient’s behalf. At this point, the email has reached the recipient’s electronic device.
• Then the email is read using POP3 or IMAP. These protocols are used with platforms such as Outlook, Gmail and so on.

Port Numbers are Entered Here:

Recommended settings:

• Incoming (IMAP): 143
• Outgoing (SMTP): 25 or 587