If you have an IMAP or IMAPS server you can “read your email” using Curl. To get started you'll first of all need to know:

• Your mail-server address.
• Your mail login.
• Your mail password.

The initial example will connect us to the IMAP server at imap.example.com, using username bobby and password tables:

curl --url "imap://mail.example.com/" --user "bobby:tables"

returns

..
..
* LIST (\HasNoChildren) "/" xen-users
* LIST (\HasNoChildren) "/" mentors-debian-org
* LIST (\HasNoChildren) "/" fairshare
* LIST (\HasNoChildren) "/" INBOX

Here we see that we've connected, and received a list of folders, including “xen-users”, “fairshare”, and the “INBOX”.

If your mail-server is running over SSL then instead of using imap:// you should set the schema to imaps://, it may be that you're using a self-signed certificate in that case you'd add --insecure to avoid checking the certificate trust-chain.

This would look like so:

curl --insecure  --url "imaps://mail.example.com/" --user "bobby:tables"

With the previous example we looked at listing mailboxes. What if we wanted to actually view a message?

To fetch a message we need the identifier of the message to fetch - so we need to find out how many messages exist, as message-IDs are sequential.

To see how many messages exist in the folder “People-Steve” we'd run this:

curl --insecure \
    --url "imaps://mail.example.com/" \
    --user "bobby:tables" \
    --request "EXAMINE People-Steve"

returns:

* OK [PERMANENTFLAGS ()] Read-only mailbox.
* 9465 EXISTS
* 3266 RECENT
* OK [UIDVALIDITY 1373146046] UIDs valid
* OK [UIDNEXT 9468] Predicted next UID

This tells us that there are 9465 messages. So we can probably assume that fetching a message with each of these IDs will work: 1, 2, 3, … 9465, & 9465.

Fetching a message is simple if you know both the folder from which it comes and the ID of the message you wish to retrieve.

We've already shown that the folder “People-Steve” contains nearly ten-thousand messages, so this next example will show us fetching the message with ID 512:

curl --insecure \
    --url "imaps://mail.example.com/People-Steve;UID=512" \
    --user "bobby:tables"

returns:

..
X-HELO: mail.cs.helsinki.fi
X-REMOTE-IP: 128.214.9.1
X-REMOTE-HOST: courier.cs.helsinki.fi
..
..
I just accidentally someone! (see facebook)
..

Fetching the message includes both the headers and the body. If you want to fetch just the headers, or a subset, things are a little fiddlier due to URL-encoding. This example gets the headers “to”, “from”, “date”, and “subject”:

curl --insecure \
    --url "imaps://mail.example.com/People-Steve;UID=512;SECTION=HEADER.FIELDS%20(DATE%20FROM%20TO%20SUBJECT)" \
    --user "bobby:tables"

returns:

Date: Sat, 14 Apr 2012 14:13:41 +0300 (EEST)
From: Steve Kemp <steve@steve.org.uk>
To: Steve Kemp <steve@steve.org.uk>
Subject: Re: Fancy a cake?

We could have avoided the use of URL-encoding and instead sent a custom-request, like so:

curl --insecure --verbose \
    --url "imaps://imap.example.com/People-Steve" \
    --user "bobby:tables" \
    --request "fetch 512 BODY.PEEK[HEADER.FIELDS (Subject)]"

returns:

..
Subject: Re: Fancy a cake?
..

The reason for avoiding custom-requests where possible is that when you're using the curl API programatically you'll discover that responses are not decoded - which is a known issue.

In the example above we'd have received zero output unless/until we added the --verbose flag. Precisely because curl has received the output from the IMAP-server but not decoded it and presented it to us.

As a quick hack the following shell-script will dump the subject of the first ten messages in the given mailbox:

#!/bin/sh
# Dump the subject of the first ten messages in the folder.
 
for id in `seq 1 10` ; do
    echo "Message ${id}"
    curl --insecure \
        --url "imaps://mail.example.com/People-Steve;UID=${id};SECTION=HEADER.FIELDS%20(SUBJECT)" \
        --user "bobby:tables"
done

This takes no account of the maximum message-ID. You could just keep going indefinitely, to dump all subjects and stop on error:

#!/bin/sh
# Dump the subject of all messages in the folder.
 
id=1
 
while true  ; do
    echo "Message ${id}"
    curl --insecure \
        --url "imaps://mail.example.com/People-Steve;UID=${id};SECTION=HEADER.FIELDS%20(SUBJECT)" \
        --user "bobby:tables" || exit
    id=`expr $id + 1`
done

#!/bin/bash
#                       /usr/local/bin/curlmail
#  http://crystalfaeries.net/posix/bin/curlmail
# celeste crystalfaery 2016-02-24 22:27:10+00:00
# https://debian-administration.org/article/726/Performing_IMAP_queries_via_curl
# read(only) IMAPS INBOX  (using ~/.netrc for password)
# (machine example.org login user password my_password)
# 1st argument is machine name (else talk to self if not specified)
# 2..n argument(s) (optional) are message number(s) to view
# e.g.: curlmail example.org 3 1 4
help=10 # this line number of file -1
# NOTE: remove the "--insecure" argument to curl if server(s) have real certificate vs self-signed certificate
# NOTE: we do not sanitize the server argument, so as-is don't make this into a cgi
 
function cleanup {
  if [ -e /tmp/$$ ]; then
    rm	/tmp/$$		# cleanup our temporary file
  fi
}
 
trap cleanup INT TERM			# cleanup our temporary file
 
case $# in
 
0)
  exec	$0 `hostname`		# talk to myself
  exit	-1			# exec doesn't return, right?
  ;;
1)
  case "$1" in
    -v)
	tail -n +4 $0 | head -n 1
	;;
    --version)
	tail -n +4 $0 | head -n 1
	;;
    -h)
	head -n $help $0 | tail -n +6
	;;
    --help)
	head -n $help $0 | tail -n +6
	;;
    *)
	let uid=0
	while let uid=$uid+1
	do	# iterate available messages
	  echo -n "${uid}: "									>> /tmp/$$
	  chmod 600										   /tmp/$$
	  curl -# --insecure -n --url \
		"imaps://${1}/INBOX;UID=${uid};SECTION=HEADER.FIELDS%20(DATE%20FROM%20TO%20SUBJECT)"	>> /tmp/$$ 2>/dev/null || break
	done 
	sed 's/\n\n/\n/g'										<  /tmp/$$ | less
	rm												   /tmp/$$
	;;
    esac
      exit
      ;;
*)
  server="$1"
  shift
  while [ $# != 0 ]
  do  # iterate requested messages
    message=`echo "$1" | tr -d -c '[:digit:]'`	# sanitize input
    shift
    rm									   /tmp/$$ 2>/dev/null
    echo -n "${message}: "							>> /tmp/$$
    chmod 600								   /tmp/$$
    curl -# --insecure -n --url "imaps://${server}/INBOX;UID=${message}"	>> /tmp/$$ 2>/dev/null
    sed 's/\n\n/\n/g'							<  /tmp/$$ | less
    rm									   /tmp/$$
  done
  exit
  ;;
esac

http://crystalfaeries.net/fae/curlmail.html