Compresses email in maildir format with check for already-compressed files

dovecot-maildir-compress.sh

#!/bin/bash

# Enable zlib in Dovecot alongside automatic writing of new emails in gzipped format

## Convert Existing Emails using process described with the pseudocode here: https://wiki.dovecot.org/Plugins/Zlib
##
##

store=.
compress=bzip2

find "$store" -type d -name "cur" | while read maildir;
do
        tmpdir=$(cd "$maildir/../tmp" &>/dev/null && pwd) || exit 1
    
        #find=$(find "$maildir" -type f -name "*,S=*" -mtime +30 ! -name "*,*:2,*,*Z*" -printf "%f\n")
        #find=$(find "$maildir" -type f -name "*,S=*" ! -name "*,*:2,*,*Z*" -printf "%f\n")
        find=$(find "$maildir" -type f ! -name "*,*:2,*,*Z*" -printf "%f\n")

        if [ -z "$find" ];
        then
            continue
        fi
    
        echo "Before compression:"
        du -h "$maildir"
    
        echo "$find" | while read filename;
        do
            srcfile="$maildir/$filename"
            tmpfile="$tmpdir/$filename"

            # if the file is not already compressed...
            "$compress" -q -t "$srcfile" > /dev/null 2>&1
            if [ $? -ne 0 ]; then
                    $compress --best --stdout "$srcfile" > "$tmpfile" &&
            
                    # Copy over some things
                    chown --reference="$srcfile" "$tmpfile" &&
                    chmod --reference="$srcfile" "$tmpfile" &&
                    touch --reference="$srcfile" "$tmpfile"
            fi
        done

        echo "$find" | while read filename;
        do
            srcfile=$maildir/$filename
            tmpfile=$tmpdir/$filename

            "$compress" -q -t "$srcfile" > /dev/null 2>&1
            if [ $? -ne 0 ]; then
                    flags=$(echo $filename | awk -F:2, '{print $2}')

                    if echo $flags | grep ',';
                    then
                        newname=$filename"Z"
                    else
                        newname=$filename",Z"
                    fi

                    dstfile=$maildir/$newname

                    if [ -f "$srcfile" ] && [ -f "$tmpfile" ];
                    then
                        #echo "$srcfile -> $dstfile"

                        mv "$tmpfile" "$srcfile" &&
                        mv "$srcfile" "$dstfile"
                    else
                        rm -f "$tmpfile"
                    fi
            fi
        done

        echo "After compression:"
        du -h "$maildir"

        find "$maildir" -type f -name dovecot.index\* -delete
done