#!/bin/cat
# $Id: FAQ.General.txt,v 1.254 2025/08/21 13:22:35 gilles Exp gilles $

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                     General FAQ for imapsync 
=======================================================================

This document is also available online at
https://imapsync.lamiral.info/FAQ.d/
https://imapsync.lamiral.info/FAQ.d/FAQ.General.txt

Questions answered in this FAQ are:

Q. Do I need to create IMAP mailboxes at the destination platform?

Q. Am I forced to publish the IMAP service on the Internet since the two
   environment are not in the same location or same LAN?

Q. What are the most important differences between the Unix shell syntax
   and the Windows batch syntax.

Q. How to install imapsync?

Q. How to upgrade imapsync?

Q. How to use imapsync?

Q. Can you give some configuration examples?

Q. How can I have commercial support?

Q. How can I have gratis support?

Q. Where I can find old imapsync releases?

Q. Where I can find free open and gratis imapsync releases?

Q. Is is legal to find imapsync gratis (or not) elsewhere?

Q. How "Facts and figures" are known 
   https://imapsync.lamiral.info/#NUMBERS

Q. I use --useuid which uses a cache in /tmp or --tmpdir, the hostnames
   host1 or host2 has changed but mailboxes are the same. Will imapsync
   generate duplicate messages on next runs?

Q. How can I speed up transfers?

Q. I see warning messages like the following:
   "Host1 Sent/15 size 1428 ignored (no header so we ignore this message.
   To solve this: use --addheader)".
   What can I do to transfer those messages?

Q. How can I try imapsync with latest Mail::IMAPClient 3.xx perl module?

Q. How can I use imapsync with Mail::IMAPClient 2.2.9 perl module?

Q. How to verify imapsync.exe I got is the right file bit per bit?

Q. Folders are not created on host2. What happens?

Q. I am interested in creating a local clone of the IMAP on a LAN 
   server for faster synchronizations, email will always be delivered 
   to the remote server and so the synchronization will be one way - from 
   remote to local. How suited is imapsync for continuous one-way 
   synchronization of mailboxes? Is there a better solution?

Q. I need to log every output on a file named log.txt

Q. Quantifier in {,} bigger than 32766 in regex; marked by <-- HERE in 
   m/(.{ <-- HERE 1,49947})(?:,|$)/ at Mail/IMAPClient.pm line 2121.

Q. Couldn't create [INBOX.Ops/foo/bar]: NO Invalid mailbox name: 
   INBOX.Ops/foo/bar 

Q. Is it possible to sync also the UIDL of the POP3 server?

Q. Is it possible to sync also the UIDs of the IMAP server?

Q. The option --subscribe does not seem to work

Q. Can Imapsync filter Spam during the sync?

Q. How to migrate from uw-imap with an admin/authuser account?

Q: How to migrate from Sun Java Enterprise System / Sun One / iPlanet /
   Netscape servers with an admin account?

Q. Is there a way to delete the destination folder when the source 
   folder is no longer there?

Q. How can I write an .rpm with imapsync

Q. Where I can read up on the various IMAP RFCs?

Now the questions again with their answers.

=======================================================================
Q. Do I need to create IMAP mailboxes at the destination platform?

A. Yes!
   Imapsync does only IMAP and there is no way to create an account 
   with the standard IMAP protocol. So you have to create them first.

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Q. Am I forced to publish the IMAP service on the Internet since the two
   environment are not in the same location or same LAN?

A. The host where you run imapsync has to contact both servers via imap.
   You are not obliged to publish the imap service on the Internet if 
   the host running imapsync can contact both imap servers via imap. 
   Use their names or their IP addresses.

=======================================================================
Q. What are the most important differences between the Unix shell syntax
   and the Windows batch syntax.

A. There are several differences between Unix and Windows
in the command line syntax. 
- Character \ on Unix versus ^ on Windows 
- Character ' on Unix versus " on Windows 

Details:

A) \ versus ^

On Unix shells you can write a single command on multiple lines
by using the escape character \ at the end of each line 
(except the last one). On Windows this character is ^

Unix example:

./imapsync \
   --host1 imap.truc.org --user1 foo --password1 secret1 \
   --host2 imap.trac.org --user2 bar --password2 secret2


Windows example:

imapsync ^
   --host1 imap.truc.org --user1 foo --password1 secret1 ^
   --host2 imap.trac.org --user2 bar --password2 secret2


Of course you can write the command on a single line without 
characters \ nor ^. I use them because the output is
better, no truncation, pretty print. It's just sugar!

In this FAQ I use \ for examples. Transcript to ^ if
you're on a Windows system.

B) Quote vs Double-quote, ie ' versus " 

On Windows the single quote character ' doesn't work
like on Unix so in the examples of this FAQ the 
command containing single quotes ' will fail on Windows.
To fix this, just replace single quotes ' by double quotes "

Also on Windows, in examples with \$1, replace 
any \$1 by $1 (remove the \ before $).

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Q. How to install imapsync?

A. Read the INSTALL files in the tarball. They are also available at
   https://imapsync.lamiral.info/#install
   and 
   https://imapsync.lamiral.info/INSTALL.d/

=======================================================================
Q. How to upgrade imapsync?

A. Do like a fresh installation.

=======================================================================
Q. How to use imapsync?

A. Read the TUTORIAL_Unix.txt file, maybe the README and, if you 
   encounter problems, the  FAQ.d/* files in the tarball.
   All are also available and updated at:
   https://imapsync.lamiral.info/#doc

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Q. Can you give some configuration examples?

A1. Basic usage is described there:
    https://imapsync.lamiral.info/#DOC_BASIC

It is:

  imapsync --host1 test1.lamiral.info --user1 test1 --password1 secret1 \
           --host2 test2.lamiral.info --user2 test2 --password2 secret2

A2. Some FAQ files contains many examples for several scenarios
    https://imapsync.lamiral.info/#doc
    (Gmail, Office365, Exchange, Darwin, etc.)

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Q. How can I have commercial support?

A. Buy support from imapsync author: Gilles LAMIRAL
https://imapsync.lamiral.info/#buy_all

=======================================================================
Q. How can I have gratis support?

A. Write to the imapsync author: Gilles LAMIRAL
https://imapsync.lamiral.info/#AUTHOR

I help all users as long as I have time to help them all, 
users who bought the support get my help first.

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Q. Where I can find old imapsync releases?

A. Search the internet or ask the author.

=======================================================================
Q. Where I can find free open and gratis imapsync releases?

A. Search the internet or ask the author.

Q. Is is legal to find imapsync gratis (or not) elsewhere?

A. Yes, the license permits it
   https://imapsync.lamiral.info/NOLIMIT

=======================================================================
Q. How "Facts and figures" are known 
   https://imapsync.lamiral.info/#NUMBERS

A. To know wether a newer imapsync exists or not, imapsync does a http 
   GET to http://imapsync.lamiral.info/VERSION
   Via the User-agent parameter it also send:

    * imapsync release
    * Perl version
    * Mail::IMAPClient version
    * Operating System

You can remove this behavior by adding option --noreleasecheck on the
command line (or by setting $releasecheck = 0 in the source code)
or by using the github release.

=======================================================================
Q. I use --useuid which uses a cache in /tmp or --tmpdir, the hostnames
   host1 or host2 has changed but mailboxes are the same. Will imapsync
   generate duplicate messages on next runs?

A. Yes

Q. How can I fix this?

A. The cache path reflects exactly hostnames or ip addresses given via
   --host1 and --host2 values. So just change the directory names 
   of host1 or host2. Use --dry to see if next runs will generate 
   duplicates.
   By default on Unix the cache is like 

   /tmp/imapsync_cache/host1/user1/host2/user2/...

=======================================================================
Q. How can I speed up transfers?

A. By using --useuid imapsync avoid getting messages headers and build
   a cache. On Unix a good thing is to add also --tmpdir /var/tmp
   to keep the cache since /tmp is often cleared on reboot.

   imapsync ... --useuid 

On Unix:

   imapsync ... --useuid --tmpdir /var/tmp/

A. Add also --nofoldersizes since the default behavior is to compute
   folder sizes. Folder sizes are useless for the transfer, just 
   useful to see what has to be done on each folder and guess when 
   the transfer will end (ETA).

A. Add also --noexpungeaftereach if you use --delete1. 
   But be warn that an interrupted transfer can lose messages 
   on host2 in a second run if you use a (silly) combination like:

   imapsync ... --delete1 --noexpunge1 --noexpungeaftereach --expunge2

Notes about --useuid

Case where building the cache first is necessary (to avoid multiples transfers)

If you run again imapsync with --useuid on a transfer  already done without 
--useuid then, to avoid messages be copied again, first run imapsync 
with --usecache but without --useuid, example scenario:

A] Running with the default options, I began without --useuid 

1) First run with default options

  imapsync ...

Too slow, I want to speed up!

2) Build the cache

 imapsync ... --usecache

3) Speed up now

  imapsync ... --useuid

B] I began with --useuid from the first time

1) First run and next runs with --useuid

  imapsync ... --useuid


Inodes number issue.

The cache is simple, it uses the file-system natively, 
it's just an empty file per message transfered.
When mailboxes are huge the cache can exhaust the number of inodes 
allowed in the filesystem, that's a limitation like limitation
size but it's less often encountered.

On Unix, to predict whether your tmpdir filesystem used by imapsync 
will support the whole cache, just run the command "df -i /var/tmp", 
if /var/tmp is the --tmpdir argument.

On windows, search and drop me a note about how to count the number 
of files allowed in the filesystem. 
It seems FAT32 supports 268 435 445 clusters.

Choosing the number of inodes allowed by a filesystem can be done 
at the creation of it with "mkfs -N number-of-inodes ..."

imapsync can predict how many messages have to be synced with the 
option --justfoldersizes (no transfer will be done)

  imapsync ... --justfoldersizes


=======================================================================
Q. I see warning messages like the following:
   "Host1 Sent/15 size 1428 ignored (no header so we ignore this message.
   To solve this: use --addheader)".
   What can I do to transfer those messages?


A1. Like suggested inline, use --addheader option. 
Option --addheader will add an header line like 
Message-Id: <15@imapsync>
where 15 is the message UID number on host1.  
Then imapsync will transfer the changed message on host2.
Duplicates won't happen on next runs.

   imapsync ... --addheader

A2. Other solution. 
Use --useuid then imapsync will avoid dealing with headers.

   imapsync ... --useuid

=======================================================================
Q. How can I try imapsync with latest Mail::IMAPClient 3.xx perl module?

A1 Run:

   cpanm Mail::IMAPClient # this uses cpanminus

   or

   cpan -i Mail::IMAPClient 
   
   or

   perl -MCPAN -e "install Mail::IMAPClient"
   

A2 If you want to install the Perl module locally in a directory

   - Download latest Mail::IMAPClient 3.xx at
     http://search.cpan.org/dist/Mail-IMAPClient/

   - untar it anywhere:
        tar xzvf Mail-IMAPClient-3.xx.tar.gz

   - Get any imapsync (latest is better).

   - run imapsync with perl and -I option tailing to use the perl
     module Mail-IMAPClient-3.xx. Example:

         perl -I./Mail-IMAPClient-3.39/lib  ./imapsync ...

     or if imapsync is in directory /path/
        perl -I./Mail-IMAPClient-3.39/lib   /path/imapsync ...

=======================================================================
Q. How can I use imapsync with Mail::IMAPClient 2.2.9 perl module?

A. Mail::IMAPClient 2.2.9 is no longer supported.
   Help yourself.

=======================================================================
Q. How to verify imapsync.exe I got is the right file bit per bit?

A. Use md5sum to check integrity of the file.
   Get md5sum.exe at http://etree.org/md5com.html

   md5sum imapsync.exe

   Then compare the checksum with the one given by the author.

=======================================================================
Q. Folders are not created on host2. What happens?

A. Do you use IMAP or POP3 with your client software?
It looks like you use POP3 instead of IMAP, POP3 sees only INBOX.


=======================================================================
Q. I am interested in creating  a local clone of the IMAP on a LAN 
   server for  faster synchronizations, email will always be delivered 
   to the remote server and so the synchronization will be one way - from 
   remote to local. How suited is imapsync for continuous one-way 
   synchronization of mailboxes? Is there a better solution?

A. If messages are delivered remotely and you play locally with the
   copy, in order to have fast access, then the synchronization can't
   be one way. You may change flags, you may move messages in 
   different folders etc. The issue described is clearly 
   two-ways sync.

   A better tool with this scenario is offlineimap, 
   designed for this issue, and faster than imapsync.


=======================================================================
Q. I need to log every output on a file named log.txt

A1. imapsync logs on a file by default, its name is given at the 
    beginning and at the end of each run. This name is unique since
    it is compound of the current date and time and user2 value. 

A2. To change this default name, use --logfile log.txt

  imapsync ... --logfile log.txt


=======================================================================
Q. Quantifier in {,} bigger than 32766 in regex; marked by <-- HERE in 
   m/(.{ <-- HERE 1,49947})(?:,|$)/ at Mail/IMAPClient.pm line 2121.

A. Do not use a bigger value than 3276 with --split1 or --split2
 
=======================================================================
Q. Couldn't create [INBOX.Ops/foo/bar]: NO Invalid mailbox name: 
   INBOX.Ops/foo/bar 

Let begin by an explanation.

Example:
sep1 = /
sep2 = .

imapsync reverts each separator automatically. 

a) All / character coming from host1 are converted to . (convert the separator)
b) All . character coming from host1 are converted to / (to avoid 
intermediate unwanted folder creation). 

So 
INBOX/Ops.foo.bar (Ops.foo.bar is just one folder name) will be translated to 
INBOX.Ops/foo/bar 

Sometimes the sep1 character is not valid on host2 (character "/" usually)

A. Try :

  --regextrans2 "s,/,X,g"

It'll convert / character to X 
Choose X as you wish: _ or SEP or 
any string (including the empty string).

This issue is automatically fixed by default since imapsync 
release 1.513, use --nofixslash2 to suppress the fix.

=======================================================================
Q. Is it possible to sync also the UIDL of the POP3 server?

A. imapsync doesn't talk POP3 but I think you mean UID in IMAP.
   See next question.

=======================================================================
Q. Is it possible to sync also the UIDs of the IMAP server?

A. No, not with imapsync, not with any IMAP client software tool.
   UIDs in IMAP are chosen and created by the server, not by the 
   client software tool. Imapsync is a client software command. 
   UIDs cannot be synced by any imap method, by design of the 
   protocol.

See the IMAP RFC9051 for more details:
https://datatracker.ietf.org/doc/html/rfc9051#name-unique-identifier-uid-messa

   UIDs may be synced via a rsync command between the imap servers but
   it implies they are the same software, among other constraints.

=======================================================================
Q. The option --subscribe does not seem to work

A1. Use it with --subscribed

A2. There is also the --subscribe_all option that subscribe to all 
    folders on host2, no matter the subscribed folders on host1.

======================================================================
Q. Can Imapsync filter Spam during the sync?

A. No, imapsync doesn't detect Spam by itself. But I've seen blogs and
   Spamassassin documentation explaining solutions to apply Spamassassin
   to a imap mailbox. So you can apply one of these solutions on the host1
   source mailbox before the imapsync run or on the destination host2
   mailbox after the imapsync transfer.

http://www.stearns.org/doc/spamassassin-setup.current.html#isbg
http://euer.krebsco.de/using-spamassassin-on-a-remote-imap-host.html
https://github.com/ook/isbg

   Imapsync can delegate this job during its IMAP syncs via the 
   --pipemess option but the underlying spam tool has to be written.
   
======================================================================
Q. How to migrate from uw-imap with an admin/authuser account?

A. Use the following syntax:

  imapsync ... --user1="loginuser*admin_user" --password1 "admin_user_password"


======================================================================
Q. How to migrate from Sun Java Enterprise System / Sun One / iPlanet /
   Netscape servers with an admin account?

A: Those imap servers don't allow the typical use of --authuser1 to use an
administrative account. They expect the use of an IMAP command called
proxyauth that is issued after login in as an administrative account.

For example, consider the administrative account 'administrator' and your
real user 'real_user'. The IMAP sequence would be:

  OK [CAPABILITY IMAP4 IMAP4rev1 ACL QUOTA LITERAL+ NAMESPACE UIDPLUS
  CHILDREN BINARY UNSELECT LANGUAGE STARTTLS XSENDER X-NETSCAPE XSERVERINFO
  AUTH=PLAIN] imap.server IMAP4 service (Sun Java(tm) System Messaging
  Server ...))
  1 LOGIN administrator password
  1 OK User logged in
  2 PROXYAUTH real_user
  2 OK Completed

In imapsync, you can achieve this by using the following options:

  --host1 source.imap.server \
  --user1 real_user \
  --authuser1 administrator \
  --proxyauth1 \
  --passfile admin.txt

======================================================================
Q: How can I write an .rpm with imapsync

A. You'll find an RPM imapsync.spec file in the directory learn/rpm/
   It has been downloaded from
   https://svn.fysik.dtu.dk/projects/rpmbuild/trunk/SPECS/imapsync.spec
   It has been tested with imapsync 1.434 (May 2011) on CentOS5 
   and RedHat RHEL5 Linux. (Thanks to Ole Holm Nielsen).
   This imapsync.spec is coming from Neil Brown work in 2007.


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