IMAP and/or POP

POP copies the email from the server, and the standard says delete the email from the server at the same time (however, gmail and maybe others have a POP option to not delete the email from the server; maybe others do as well).

IMAP keeps the email on the server. When you connect it initially ONLY downloads the header (to, from, cc, date, subject). When you select the message, it then downloads the email body for you to read, but it keeps the mail on the server. When you download the body the IMAP server marks the email read.

When you move the mail to a folder, it does the move on the server.

Mail clients do have the ability to copy the mail to local storage, but that is not the default.

POP was fine in the good old days when mail servers did not have a lot of disk space, and when people ONLY used a single device to do all their email.

Today, when people having iPhones, laptops. work computers, etc... the IMAP protocol allows the user to access their mail from anywhere and have a consistent view.

Hey FH678,
I understand that you have some questions regarding the differences between POP and IMAP. You are on the right track as far as understanding this but I can clear this up for you.
Let's start with POP. The way that works is that everything is kept on the server until it is downloaded to your computer. If you have more than one device, like you iPhone, then you will need to delete them from both your computer and iPhone.
With IMAP, that is something that will be in sync all the time as long as you have an internet connection. The emails are always stored on the server and when you check your email, it will verify that everything is the same. So if you delete a message on your iPhone, it will not show up on your Mac.
Take care

FH678 wrote:

Thank You BobHarris. That was very helpful. So if I deactivate the POP account, I take it I will not lose any messages, correct? They'll all be available on the IMAP version of the same email account?

Be careful here.

First if you tell Apple Mail to delete the POP account, I think it will delete ALL the mail messages it has stored locally on your Mac (it will not change anything on the mail service, but locally you have copies of your mail in your home folder -> Library -> Mail, and deleting a POP account in Apple Mail might delete your copies).

As for your mail service. A lot depends on what you are using for a mail service, and if they still have copies of your mail on their servers. As I said, the POP (Post Office Protocol) is suppose to delete email on the server after giving it to the client. If your mail serivce does not delete the original email, then yes it would still be on your mail server.

I would setup the IMAP account first, and verify that you can access all your mail on the mail server before I did anything to the POP account.

I may have used the wrong word. I wasn't considering deleting the POP account, just disabling it. Or does that amount to the same thing? In the Mail preferences, there's a checkbox that says "enable this account" and I thought that if I disabled it, the account would still exist but not show up in my list of accounts in Mail.

I think you are correct that disabling will allow you to re-enable, and should not delete the local mail for that account stored on your Mac.

POP is redundant, except that it does always copy your mail from your mail service to your Mac. If you are a person that hordes their mail, this is a way to always make sure you have a copy on your Mac. And if having both POP and IMAP to the same mail service does not cause duplicate mail messages to appear, creating confusion, then if it makes you happy, go for it.

NOTE: It is possible to copy IMAP messages to your Mac, but I think it is a manual process, or something you have to maybe play with Mail rules to make happen.

And if you are happy not keeping local copies (they do take up space), then go all IMAP once you are sure you have all your mail on the server.

FH678 wrote:

I do tend to keep most emails, but I move them manually anyway into folders for different projects and senders, etc. I take it I just need to move them on my computer before deleting them from my phone if it's IMAP.

Yup.

And I did check. You can create Apple Mail rules to copy mail to local folders (not to be confused with IMAP folders kept on the mail server). Of course this is a theory, as I did not actually setup any rules to test it.

BobHarris wrote:

FH678 wrote:

I do tend to keep most emails, but I move them manually anyway into folders for different projects and senders, etc. I take it I just need to move them on my computer before deleting them from my phone if it's IMAP.

Yup.

And I did check. You can create Apple Mail rules to copy mail to local folders (not to be confused with IMAP folders kept on the mail server). Of course this is a theory, as I did not actually setup any rules to test it.

I keep a local Archive folder (On My Mac) and use a Mail rule to move older mail off of the IMAP server to the local archive. It's simple to setup and works well.

FH678 wrote:

The Archive thing seems to be new in Mail 9. I'll have to look into that. Thanks.

I am not referring to "the archive thing"

Make a local folder, locate it On Your Mac, call it whatever you want and then move mail to it as needed,

"The archive thing" won't do what you want, don't trust labels, they're just labels.

The problem with IMAP archives (as offered by Gmail and iCloud etc) is that they are located on the same server as the rest of the account, which hardly fits my description of an archive (capitalized or otherwise). The simplest method of moving is via a smart folder with date filters.