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IMAP is a surprisingly simple protocol to implement, particularly in an environment like the Translator. Here are some basic concepts:

That’s a key concept in understanding that IMAP allows you to access your email from multiple devices like your phone and computer.

It also means that these email servers can end up storing a lot of data.

IMAP servers maintain a list of the emails which you can access via a unique ID number for each one

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title	IMAP is an protocol for email where the Email remains stored on the server which you can access from multiple devices

stands for Internet Message Access Protocol usually between an email client and an email server

It’s a protocol intended to let a email program communicate and get email from a email server.

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title	It is a TCP/IP protocol which means it's over a network and consists of a stream of data back and forth

A TCP/IP stream gives guaranteed delivery of the order of data.

Guaranteed means the TCP/IP protocol is designed to try and help the data reach the other side back and forth in a way that the data and order of the data is preserved.

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title	IMAP is a TCP/IP based protocol that is conversationalconversational protocol

IMAP is a conversation between the client and the server. One opens up a TCP/IP stream. The server says “hello” and then the client says who they are and if the server accepts the proof of who the client says they are then the client can ask the server to do various commands.The client and server talk to each other using the language of IMAP.

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title	The IMAP client connects and the IMAP server says Hello!

This is a common pattern with many TCP/IP protocols - it’s a way for the server to say - Hi - I speak your language and let’s begin a conversation.

It’s like going up to someone and saying Hola! It signals you are ready for a conversation and that you speak Spanish.

This is what we’d see say with a Gmail IMAP server:

Code Block
* OK Gimap ready for requests from 69.196.142.158 ql9mb2511069qvb

This is IMAP for Hello!

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title	Next we need to verify our identity since we don't want to give sensitive information to anyone

We need to authenticate - usually with a user name and password. We send a LOGIN command which looks like this:

Code Block
a01 LOGIN aryn.wiebe@interfaceware.com lkjllkjddkdjsfdhgh\r\n

So IMAP messages start with a unique code for each message we send to the server. In this case a01 - this unique ID that we use to track the command we have sent so when we get a reply from the server then we know what the topic was.

Notice the \r\n newline sequence? There is an interesting story behind that.

Remember that question I asked you?

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title	Then we get the response back to what we said:

Code Block

* CAPABILITY IMAP4rev1 UNSELECT IDLE NAMESPACE QUOTA ID XLIST CHILDREN X-GM-EXT-1 UIDPLUS COMPRESS=DEFLATE ENABLE MOVE CONDSTORE ESEARCH UTF8=ACCEPT LIST-EXTENDED LIST-STATUS LITERAL- SPECIAL-USE APPENDLIMIT=35651584
a01 OK aryn.wiebe@interfaceware.com authenticated (Success)

Take special note of the a01 OK.

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title	Each response comes back with ID plus code - either OK, NO or BAD

The ID matches up with the ID we sent before as the client - so this is part of the conversation of telling the client whether the last command it sent was OK or refused NO, or was formatted incorrectly - i.e. BAD an error.

So IMAP clients typically need a method of generating these IDs either randomly or in sequence.

An IMAP client also needs a routine to read the data back from the client to get the data.

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title	Then the client can issue whatever commands they like

It’s a conversation after all - no two conversations are alike.

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title	Select INBOX command - also tells us what the highest ID mail that we can request

Line 8 tells us we have successfully selected the INBOX.

Line 4 also tells us the highest ID mail which exists is 82838.

Code Block

* FLAGS (\Answered \Flagged \Draft \Deleted \Seen $NotPhishing $Phishing)
* OK [PERMANENTFLAGS (\Answered \Flagged \Draft \Deleted \Seen $NotPhishing $Phishing \*)] Flags permitted.
* OK [UIDVALIDITY 1] UIDs valid.
* 82838 EXISTS
* 0 RECENT
* OK [UIDNEXT 84128] Predicted next UID.
* OK [HIGHESTMODSEQ 8669111]
a02 OK [READ-WRITE] INBOX selected. (Success)

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title	Fetch an email

Here is a sample of an IMAP Fetch response:

Note we can clearly see the header, body, and success response all separated by a boundry (001a113da73205a6ea056272f2ab). We can use this boundary to help parse the email and isolate its parts.

Code Block

* 1 FETCH (BODY[] {4835}
MIME-Version: 1.0
x-no-auto-attachment: 1
Received: by 10.25.43.137; Wed, 10 Jan 2018 13:45:09 -0800 (PST)
Date: Wed, 10 Jan 2018 13:45:09 -0800
Message-ID: &lt;CAP14fq11RQ3+xEZk7uSmWb4rv1oEDdX66fuq7wJJbkxFv+u1fA@mail.gmail.com&gt;
Subject: Hey!
From: real.person@gmail.com;
To: Aryn Wiebe &lt;aryn.wiebe@interfaceware.com&gt;
Content-Type: multipart/alternative; boundary="001a113da73205a6ea056272f2ab"

--001a113da73205a6ea056272f2ab
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

Hi Aryn

This is a sample email! 

Thanks, 

--001a113da73205a6ea056272f2ab
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE html>
...

--001a113da73205a6ea056272f2ab--)
a03 OK Success

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title	What other commands are possible - Chat GPT is helpful resource here

Lot’s of commands are possible like getting a summary of an email (can be helpful to avoid loading a very big email).

You can delete emails.

You can probably filter on them. Ask Chat GPT - it knows a lot about IMAP

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title	The best way to understand the protocol is to open up the Email IMAP IMAPemail Feeder and look at it in the translator

You’ll never get a better way to see how IMAP really works.

Load the IMAP Email Feed and use The string viewing window and Annotation Windows you really get to see how it works.

That’s important since it’s also how you can diagnose problems.

I don’t know about you but I get very frustrated with the spinning disc I often get on my Apple Email client on my phone with no visibility as to what is going wrong.

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title	Chat GPT is also a pretty helpful resource if you want information on the different IMAP commands you can issue

That’s how I got started with this little project.

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