Why POP3 protocol survives?

Question

I am getting some basic knowledge e-mail protocol. It seems that IMAP is more powerful than POP3. Then, why POP3 protocol survives? and it is still supported by popular email service like GMail?

Thanks.

Answer 1

Because POP3 does not need as much storage on the server side. And because is is more simple and easy to implement.

Answer 2

Many email services (such as those provided by ISPs) only offer a limited size mailbox. This makes it necessary to download your messages to your computer to be able to store the large number of emails that are common these days.

Answer 3

Read the IMAP specification(s) and you know. POP3 is more KISS than IMAP.

Answer 4

I'd rather have my email on my PC than on an ISPs server. It's a matter of privacy.

Answer 5

Yahoo mail still does not offer IMAP. My guess is that it's because I'm more likely to use their site than Outlook, meaning I'll have to see their ads.

Answer 6

I think part of it is that IMAP is usually used in scenarios where the emails are retained on the server, whereas POP is used almost exclusively for situations where the email is downloaded to the local machine, which is what most ISPs providing email facilities for their customers want you to do (and also what most of the customers probably want as well, although less so as they get more exposure to the Internet and things like gmail and yahoo, etc.)

Another reason it is probably preferred by email providers is that it does polling, much like an RSS news reader. The POP client will open a TCP/IP connection to the server, authenticate itself, ask for any email and do whatever processing it needs, and then close the connection.

IMAP clients generally keep one or more TCP/IP sockets open with the server the whole time they are running, taking up those resources. Yet another reason for ISPs to prefer POP.

Google mail supports both POP and IMAP protocols.

(P.S. I do not mean to sound like I am having a go at ISPs. I think the reasons I've attributed to them above are very pragmatic and sensible.)

Answer 7

A few reasons:

1. POP3 does need far less server side storage.
2. POP3 is much easier to implement.
3. POP3 is private by default (it assumes that you want to delete email off the server after downloading it).
4. Initially almost all ISPs had tiny storage limits (since their are free large storage email services this matters less now) so deleting emails that you downloaded was a must.
5. (for completeness - thanks Evan) POP clients open a TCP/IP connection to the server, authenticates itself, asks for any email and does whatever processing it needs, and then close the connection. IMAP clients generally keep one or more TCP/IP sockets open with the server the whole time they are running, taking up those resources.