Very simple Python script to 1st dump all emails within an IMAP account to files, and extract header and attachments from the dumped email files.

maildump.py

#!/usr/bin/env python
#
# maildump.py
#
# Very simple Python script to
# 1st dump all emails within an IMAP account to files, and
# 2nd extract header and attachments from the dumped email
# files.
#
# This code bases on:
# - the script of Rob Iwancz (robulouski) 
#   (see https://gist.github.com/robulouski/7442321 )
# - and on an example from the Python documentation
#   (see https://docs.python.org/3/library/email-examples.html)
#
#
# This code is released into the public domain.
#
# honel // September 02, 2014
#
import sys
import imaplib
import getpass
import email
import mimetypes
from email.parser import Parser
from numpy import asarray
from time import sleep

#
# Edit the following lines with the respective IMAP
# account information and then run the program.
#
IMAP_SERVER = 'imap.gmail.com' # IMAP server
EMAIL_ACCOUNT = "notatallawhistleblowerIswear@gmail.com" # Login name
OUTPUT_DIRECTORY = './out' + '/' # directory for dumped emails, make sure it ends with a slash 
PASSWORD = getpass.getpass() # do not edit this line


#
# BEGIN
#
def filename(num,filetype,email_folder):
    """
    Generate a string to use as filename
    """
    DIGITCOUNT=4         # number of leading zeros 
    filename= OUTPUT_DIRECTORY + email_folder + 'mail-' +  str(num).zfill(DIGITCOUNT)  +  filetype
    return filename

def listMailboxes(M):
    """
    Return list of mailboxes
    """
    rv, mailboxes = M.list()
    if rv != 'OK':
       sys.exist(5)
    mailboxlist=[]        
    for mailbox in mailboxes:
        mailboxlist.append(mailbox.split('"')[-2])
    return mailboxlist

def postprocess_mail(num,folder):
    """
    Extract header and attachments from dumped files
    """
    fileRead=open(filename(num,".eml",folder), 'r')
    msg_headers = Parser().parse(fileRead)
    fileRead.close()
    fileWrite = open(filename(num,"-head.txt",folder), 'wb')
    fileWrite.write('Date: %s\n' % msg_headers['date'])
    fileWrite.write('From: %s\n' % msg_headers['from'])
    fileWrite.write('To: %s\n' % msg_headers['to'])
    fileWrite.write('CC: %s\n' % msg_headers['cc'])
    fileWrite.write('BCC: %s\n' % msg_headers['bcc'])
    fileWrite.write('\n')
    fileWrite.close()
    fileRead = open(filename(num,".eml",folder), 'r')
    msg = email.message_from_file(fileRead)
    fileRead.close()
    counter = 1
    for part in msg.walk():
	        if part.get_content_maintype() == 'multipart':
	           continue                                          # multipart/* are just containers
	        fname = part.get_filename()
		if not fname:
		       ext = mimetypes.guess_extension(part.get_content_type()) 
		       if ext!= None :
			  fname = 'part-'+str(counter).zfill(2)+ext
		       else:
			  fname = 'part-'+str(counter).zfill(2)+".none"
		fname=fname.replace("/", "-")
		counter +=1
		fileWrite = open(filename(num,"-"+fname,folder), 'wb')
		if not part.get_payload(decode=True)==None:
                    fileWrite.write(part.get_payload(decode=True))
	        else: 
	    	    print "Attachment of mail /", filename(num,".eml",folder), " is empty:", fname
		fileWrite.close()

def process_mailbox(M,folder):
    """
    Dump all emails in the folder to files in output directory.
    """
    rv, data = M.search(None, "ALL") # filter list of eMails, e.g.,
                                     # rv, data = M.search(None,'(FROM "Alice")')
                                     # rv, data = M.search(None,'(TO "Bob")')
    mailcount= asarray(data[0].split(" "))[-1]

    if rv != 'OK':
        print "No messages found!"
	sys.exist(1)
        return

    for num in data[0].split():
        rv, data = M.fetch(num, '(RFC822)')
        if rv != 'OK':
            print "ERROR getting message", num
	    sys.exit(10)
            return
        print "Processing Message ", num, " Of ", mailcount 
        fileWrite = open(filename(num,'.eml',folder), 'wb') # open a file to which email is dumped
        fileWrite.write(data[0][1]) # dump email
        fileWrite.close() # close file to which email was dumped to
	postprocess_mail(num,folder) # post-process dumped message

def main():
    M = imaplib.IMAP4_SSL(IMAP_SERVER)
    M.login(EMAIL_ACCOUNT, PASSWORD)
    print "Names of the found " + str(len(listMailboxes(M))) + " Folders:",  listMailboxes(M)
    print "Programm will proceed in 10 seconds. Press CRTL+C to cancel program now."
    sleep(10)
    for mailbox in listMailboxes(M):
        rv, data = M.select(mailbox)
        if rv == 'OK':
            print "======================="    
    	    print "Processing mailbox: ", mailbox
            print "======================="
            process_mailbox(M,mailbox)
            M.close()
        else:
            print "ERROR: Unable to open mailbox ", rv
    M.logout()

if __name__ == "__main__":
    main()
#
# END
#

Convert dumped eMails into PDF documents:
Use the python "txt2pdf.py" program together with my short bash script:

#!/bin/sh
for ((i=1;i<=NUMBEROFFILES;i++)); do 
    filename0="$(printf "FOLDERmail-%04d.eml" "$i")"
    filename1="$(printf "FOLDERmail-%04d-head.txt" "$i")"
    filename2="$(printf "FOLDERmail-%04d-part-01.ksh" "$i")"
    filename3="$(printf "FOLDERmail-%04d-part-01.html" "$i")"
    filename4="$(printf "FOLDERmail-%04d-text.txt" "$i")"
    echo $filename0 > $filename4
    echo >> $filename4
    cat $filename1 $filename2 $filename3 >> $filename4
    python txt2pdf.py  $filename4
    rm $filename1
    rm $filename2
    rm $filename3
    rm $filename4

This bash script is a quick and dirty solution.
As such, it requires adaptation: NUMBEROFFILES, FOLDER and %04d are hard coded into the script and require manual modification. NUMBEROFFILES represents the total number of eMails in the specified IMAP folder. %04d is responsible for generating file names with leading zeros (this value corresponds to the line DIGITCOUNT=4 in the python script). Finally, FOLDER stands for the directory in which the downloaded eMails can be found.