IMAP does not update it's Folder status

Question

I want to read E-Mails from an IMAP-Server with curl (BashScript, which is using curl).

My problem is: After moving an E-Mail the IMAP-Server does not update, so that, if I examine the inbox, the IMAP Server shows me the old amount of messages, containing in the INBOX.

To clear my problem, here is some example-Code:

function delete_mail_id() {
     curl --insecure \
          --url "${SERVER}/INBOX" \
          --user "${USER}:${PASSWD}" \
          -X "STORE ${1} +Flags \Deleted" 1>/dev/null 2>/dev/null
}
function copy_mail_id_to() {
    curl --insecure \
         --url "${SERVER}/INBOX;UID=${1}" \
         --user "${USER}:${PASSWD}" \
         -X "COPY ${1} INBOX/${2}" 1>/dev/null 2>/dev/null
}
function move_mail_id_to() {
    copy_mail_id_to "${1}" "${2}"
    delete_mail_id "${1}"
}
function wait_for_mail_move(){
    TEMP=$( tempfile )
    while true; do
        fetch_first_mail > $TEMP
        if [ "$( grep 'Message-ID:' $TEMP )" != "${1}" ]; then
            break
        else
            sleep 1
        fi
    done
    rm $TEMP
}

Now after moving an E-Mail I wait for the mail to move, but it seems to be an endless loop. Now the funny part: If I look the mails manually through my webmailer the loop ends and the mails are moved one by one (I have a loop, so all the mails should be sorted in other Folders).

Somehow the IMAP only moves the Mails if I check it through the webmailer, but doesn't do it, if I don't check it. This should be automated, so, can anyone explain to me, why this is happening and what I can do about it?

Did you call expunge? Mails don't delete until expunge is called. — Max
send the 'EXPUNGE' command? Presumably with -X like you call other commands. However don't call it until you're done, because EXPUNGEing messages will cause all the IDs to shift (when message 3 is deleted, message 4 becomes 3.) This is why it doesn't happen automatically. — Max

Max Max · Accepted Answer · 2016-11-09T21:16:15

Messages do not actually delete until someone sends an EXPUNGE command. In the mean time, they are just marked as a deleted message. Other clients or webmail systems have sent the EXPUNGE, which is why you then see changes.

The reason for this behaviour is that the message sequence numbers will change when EXPUNGE is processed: when message 3 is expunged from the mailbox, message 4 will become message 3, and message 5 will become message 4, and so on. It also allows users to potentially undelete messages.

You will likely want to wait until you've done all your message move operations, then call expunge, so your message sequence numbers don't change when you don't expect it.

IMAP does not update it's Folder status

1 Answers