When configuring email clients, Apple Mail or Windows Live, for example, the option will be given to use either POP or IMAP.
What’s the difference between POP and IMAP?
POP and IMAP are both protocols for the collection and storage of emails. But their approach differs.
The simplest way of considering the difference between the two is what happens to the email on the mail server.
In the simplistic view:
- POP email retrieves the email from the server downloading it to the local computer.
- IMAP leaves the email on the server taking as copy the headers: who sent the email, it’s title and such like.
POP Email
The POP email protocol is the older of the two.
The advantages and disadvantages of using the POP email protocol are linked to the downloading of the whole email and the mailbox interaction.
The POP protocol only interacts with the mailbox’s inbox. There are no draft emails.
There is no coordination between devices. Each is operating dependently. Actions performed in the app don’t affect email on the email server. Therefore when an email is viewed on one device its not illustrated as read on another.
This could be viewed as the synchronisation being one way only: from the server to the device.
POP allows the email headers to be downloaded separately rather than the whole email. This can be more efficient. Particularly where large emails are often received.
Advantages
A copy of emails are automatically downloaded to the local email client programme.
Unless configured to also delete from the server, emails can be moved and deleted in the email client program without affecting those on the server.
Good for long term retention of emails.
Disadvantages
Can be harder to configure.
If POP was chosen due to a restriction of the mailbox size then the configuration of the email clients will need to take this into account.
Access to the mailbox folders is limited. With only emails within the inbox can be downloaded.
A copy of the sent email is only available on the sending device’s email client program.
If the mailbox size is restricted setting the wrong delete period on the master computer might mean a gap in the emails downloaded on a given client computer
Email drafts created are not available across multiple devices, only on the one where created.
Because the email is downloaded from the server care should be taken to ensure that only one device is configured to delete the email. I like to set a master device which also deletes emails older than, for example a year. This is dependant upon the number and size of emails received and the mailbox size.
If you are using a mailbox provided by your website host or as a part of your ISP package then the available space will be limited. Downloading your emails from the mail server will reduce the size of those stored on the mailbox on the server.
IMAP Email
The IMAP protocol is the newer of the two protocols. It allows you to remotely access and manage your email. What you do in the app affects email on the email server.
It is the full interaction between the email client app and the server which makes the IMAP protocol much different to the POP protocol.
Advantages
Emails are retained on the hosting mail server.
Adding a new computer with a new email configuration will allow that client to collect all of the existing emails. This includes incoming, outgoing and drafts folders.
Moving or deleting emails within the email client program may be reflected on the server.
Emails are retained on the server
Each connected email client program can access all of the mailbox folders.
There is a record of sent emails.
The mail server coordinates the status of emails. When an email is read on one device its status is reflected on all others.
Disadvantages
Requires a larger mail box size over time as all emails are left on the server. Don’t forget this includes the rubbish bin, draft folder and sent folder. Some email clients allow timed deletion of emails on the server.
References
IMAP (Internet Message Access Protocol)
POP (Post Office Protocol)
