First just to be clear, when I say client I am referring to a locally installed client on your machine. My current client is Claws Mail, my absolute favorite client was PocoMail and is what I used before I switched to Claws Mail, sadly PocoMail is no more.
I refer to the web interface on a server as a exactly that. That is what you are using when you access your email via your browser.
said by bbear2:
So are you saying that with POP3, you have the option of your email client deleting messages off of the server;
Yes. When you do a "Get Mail" from the client. (Wording varies from client to client.) POP protocol was designed to simply download all messages from the server Inbox, then delete them from the server. Most clients by default delete messages from the server when using POP3. Many people do not understand this and wonder what happened to their messages on the server. POP3 also only works with one folder at a time. This is normally the Inbox. Back in the old days the Inbox was all you had anyway.
Claws Mail, PocoMail, Thunderbird and Outlook all delete messages from the server by default. In the case of Claws Mail, it has this receive option: "Remove messages on server when received" (checked), with "Remove after __ days __ hours" (set to 7 days). PocoMail's has "Leave Mail on Server" (not checked) with sub-options to "Remove after __ days (not checked, set to 0) and "Remove from server when emptied from Trash". (not checked). Thunderbird has "Leave messages on server" (checked) and two sub-options "For at most __ days" (checked, set to 14) and "Until I delete them" (checked). Outlook simply has "Leave a copy of messages on the server" (not checked).
Now there are services such as Gmail and Inbox.com that do not follow the rules. With Gmail you have to tell Gmail in it's settings what to do with messages that are POP'd. With Inbox.com, I need to log in periodically to delete messages from the Inbox as it ignores the POP3 DELE command "for my own good" as they put it.
but with IMAP that option doesn't exist.
Depends on your email client. Some do, some don't, have the option. My current client does not. The one I used before this one did. Anyway IMAP was not designed to be "popped". As in fetch and delete with a "Get Mail"
IMAP is completely different than POP3. It main purpose is to synchronize between the client and the server. When I use the servers web interface for reading new messages, sending messages, deleted messages, moving messages to other folders in the account, these changes will not be seen in my client until the next time I connect to the server. When I do a "Get Mail" in my client, for example, it connects to the server and synchronizes with all of my message folders on the server. When it's finished, my local client message store is the same as my server message store.
When I use my client I am normally connected so changes in my client are instantly reflected on the server. So reading, send, moving, deleting, marking as spam, etc are reflect on the server in real time (or at least as fast as my connection allows).
If I am not connected to the Internet, all of the messages since my last connection are available to read, print, delete, etc.; obviously any new messages would not be there, nor will I be able to send. I can queue messages for sending when I am connected though. When I connect, those changes are synchronized with the server.
Keep in mind some of what I have described above about IMAP depends on the client and how it is set up. Also some servers, Gmail for example, do not follow the rules.
And then in both cases you could use something like Outlook and have the email downloaded to your local client and read the emails directly from there. Do I have this right?
Yes, that is what I do right now. Of course you have this right. Though I would not call it a right per-say. Outlook has both POP3 and IMAP capabilities. I used Outlook back in my working days, but mostly via an exchange server. When I say Outlook I am referring program Outlook, not Outlook.com.
As another example of my use of IMAP with one of my organizational accounts I have Claw Mail setup to use IMAP on the organizations laptop. There are times I want to access that account from this computer I am typing on now. I simply log in via my browser and do what I need to do. Later, when I am on the laptop I can "Get Mail" using Claws Mail to synchronize it with what ever I did while working from this computer via the web interface.
One last thing. With IMAP it is critical that you have some sort of archive or backup of the messages on your local computer saved outside that IMAP account. If ProviderX some how deletes all of your messages on the server, and you connect locally that could potentially wipe out your local messages too. Again this depends on how you have your client setup. I have a daily backup system in place.
Hope I didn't over do it on my explanation. --
Living in Paradise!!