IMAP: Edit your email directly on the server
When you check your emails with an IMAP connection, you preview, access and manage your emails directly on the server.
Pros:
You can pre-visualize your email, which avoids you to occupy the bandwidth by downloading the message and its attachments entirely (the use of this protocol is advised if you have a limited or recalcitrant Internet connection);
As messages are stored on the server, you can view and manage your emails from multiple computers or smartphones;
A backup of the server and its data is usually performed regularly. In this way, if you accidentally delete an email, your administrator can retrieve it;
Most email clients have a cache feature that allows you to view your emails offline.
Cons:
If you have limited online storage space, you should regularly delete some emails to avoid reaching your volumetric threshold.
POP: Automatically download your emails to your computer
When you check your emails with a POP connection, new messages are downloaded to your computer in a file (such as .PST extension under Outlook) and they are removed from the server (1).
(1) In the POP configuration, by default the mail client downloads the message and then deletes it from the server. However, it is possible to set the application to leave a copy of the message on the server.
Pros:
You do not care about the online space available. As your emails are downloaded locally, you can keep as many emails as your computer can store;
You can view and manage your emails without an internet connection.
Cons:
If someone sends you a large message, you automatically download the entire message, which can saturate the bandwidth;
You cannot view the history of your messages anywhere other than on your computer;
If one day you lose or delete items and no backup system has been installed on your computer, you will not be able to recover them.
IMAP: Edit your email directly on the server
When you check your emails with an IMAP connection, you preview, access and manage your emails directly on the server.
Pros:
You can pre-visualize your email, which avoids you to occupy the bandwidth by downloading the message and its attachments entirely (the use of this protocol is advised if you have a limited or recalcitrant Internet connection);
As messages are stored on the server, you can view and manage your emails from multiple computers or smartphones;
A backup of the server and its data is usually performed regularly. In this way, if you accidentally delete an email, your administrator can retrieve it;
Most email clients have a cache feature that allows you to view your emails offline.
Cons:
If you have limited online storage space, you should regularly delete some emails to avoid reaching your volumetric threshold.
POP: Automatically download your emails to your computer
When you check your emails with a POP connection, new messages are downloaded to your computer in a file (such as .PST extension under Outlook) and they are removed from the server (1).
(1) In the POP configuration, by default the mail client downloads the message and then deletes it from the server. However, it is possible to set the application to leave a copy of the message on the server.
Pros:
You do not care about the online space available. As your emails are downloaded locally, you can keep as many emails as your computer can store;
You can view and manage your emails without an internet connection.
Cons:
If someone sends you a large message, you automatically download the entire message, which can saturate the bandwidth;
You cannot view the history of your messages anywhere other than on your computer;
If one day you lose or delete items and no backup system has been installed on your computer, you will not be able to recover them.