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Manual Reference Pages  -  IMAPSYNC (1)

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imapsync - IMAP synchronisation, sync, copy or migration tool. Synchronises mailboxes between two imap servers. Good at IMAP migration. More than 66 different IMAP server softwares supported with success, few failures.

$Revision: 1.678 $



 To synchronize the source imap account
   "test1" on server "" with password "secret1"
 to the destination imap account
   "test2" on server "" with password "secret2"

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


 Imapsync works under any Unix with perl.
 Imapsync works under Windows (2000, XP, Vista, Seven)
 as a standalone binary software called imapsync.exe
 Imapsync works under OS X as a standalone binary
 software called imapsync_bin_Darwin.

 Purchase latest imapsync at

 Youll receive a link to a compressed tarball called imapsync-x.xx.tgz
 where x.xx is the version number. Untar the tarball where
 you want (on Unix):

 tar xzvf  imapsync-x.xx.tgz

 Go into the directory imapsync-x.xx and read the INSTALL file.
 As mentioned at
 the INSTALL file can also be found at
 It is now split in several files for each system


To get a description of each option just run imapsync with no argument, like this:


This description of options is also available at and is reproduced here:

 usage: ./imapsync [options]

 Several options are mandatory.
 str means string
 int means integer
 reg means regular expression
 cmd means command

 --dry               : Makes imapsync doing nothing, just print what would
                       be done without --dry.

 --host1        str  : Source or "from" imap server. Mandatory.
 --port1        int  : Port to connect on host1. Default is 143, 993 if --ssl1
 --user1        str  : User to login on host1. Mandatory.
 --showpasswords     : Shows passwords on output instead of "MASKED".
                       Useful to restart a complete run by just reading the log.
 --password1    str  : Password for the user1.
 --host2        str  : "destination" imap server. Mandatory.
 --port2        int  : Port to connect on host2. Default is 143, 993 if --ssl2
 --user2        str  : User to login on host2. Mandatory.
 --password2    str  : Password for the user2.

 --passfile1    str  : Password file for the user1. It must contain the
                       password on the first line. This option avoids to show
                       the password on the command line like --password1 does.
 --passfile2    str  : Password file for the user2. Contains the password.

 --ssl1              : Use a SSL connection on host1.
 --ssl2              : Use a SSL connection on host2.
 --tls1              : Use a TLS connection on host1.
 --tls2              : Use a TLS connection on host2.
 --debugssl     int  : SSL debug mode from 0 to 4.

 --timeout1     int  : Connection timeout in seconds for host1.
                       Default is 120 and 0 means no timeout at all.
 --timeout2     int  : Connection timeout in seconds for host2.
                       Default is 120 and 0 means no timeout at all.

 --authmech1    str  : Auth mechanism to use with host1:
                       PLAIN, LOGIN, CRAM-MD5 etc. Use UPPERCASE.
 --authmech2    str  : Auth mechanism to use with host2. See --authmech1

 --authuser1    str  : User to auth with on host1 (admin user).
                       Avoid using --authmech1 SOMETHING with --authuser1.
 --authuser2    str  : User to auth with on host2 (admin user).
 --proxyauth1        : Use proxyauth on host1. Requires --authuser1.
                       Required by Sun/iPlanet/Netscape IMAP servers to
                       be able to use an administrative user.
 --proxyauth2        : Use proxyauth on host2. Requires --authuser2.

 --authmd51          : Use MD5 authentification for host1.
 --authmd52          : Use MD5 authentification for host2.
 --domain1      str  : Domain on host1 (NTLM authentication).
 --domain2      str  : Domain on host2 (NTLM authentication).

 --folder       str  : Sync this folder.
 --folder       str  : and this one, etc.
 --folderrec    str  : Sync this folder recursively.
 --folderrec    str  : and this one, etc.

 --folderfirst  str  : Sync this folder first. --folderfirst "Work"
 --folderfirst  str  : then this one, etc.
 --folderlast   str  : Sync this folder last. --folderlast "[Gmail]/All Mail"
 --folderlast   str  : then this one, etc.

 --nomixfolders      : Do not merge folders when host1 is case sensitive
                       while host2 is not (like Exchange). Only the first
                       similar folder is synced (ex: Sent SENT sent -> Sent).

 --skipemptyfolders  : Empty host1 folders are not created on host2.

 --f1f2    str1=str2 : Force folder str1 to be synced to str2.
 --include      reg  : Sync folders matching this regular expression
 --include      reg  : or this one, etc.
                       in case both --include --exclude options are
                       use, include is done before.
 --exclude      reg  : Skips folders matching this regular expression
                       Several folders to avoid:
                        --exclude fold1|fold2|f3 skips fold1, fold2 and f3.
 --exclude      reg  : or this one, etc.

 --subfolder2   str  : Move whole host1 folders hierarchy under this
                       host2 folder  str    .
                       It does it by adding two --regextrans2 options before
                       all others. Add --debug to see whats really going on.

 --regextrans2  reg  : Apply the whole regex to each destination folders.
 --regextrans2  reg  : and this one. etc.
                       When you play with the --regextrans2 option, first
                       add also the safe options --dry --justfolders
                       Then, when happy, remove --dry, remove --justfolders.
                       Have in mind that --regextrans2 is applied after prefix
                       and separator inversion.

 --tmpdir       str  : Where to store temporary files and subdirectories.
                       Will be created if it doesnt exist.
                       Default is system specific, Unix is /tmp but
                       its often small and deleted at reboot.
                       --tmpdir /var/tmp should be better.
 --pidfile      str  : The file where imapsync pid is written.
 --pidfilelocking    : Abort if pidfile already exists. Usefull to avoid
                       concurrent transfers on the same mailbox.

 --nolog             : Turn off logging on file
 --logfile      str  : Change the default log filename (can be dirname/filename).
 --logdir       str  : Change the default log directory. Default is LOG_imapsync

 --prefix1      str  : Remove prefix to all destination folders
                       (usually INBOX. or INBOX/ or an empty string "")
                       you have to use --prefix1 if host1 imap server
                       does not have NAMESPACE capability, so imapsync
                       suggests to use it. All other cases are bad.
 --prefix2      str  : Add prefix to all host2 folders. See --prefix1
 --sep1         str  : Host1 separator in case NAMESPACE is not supported.
 --sep2         str  : Host2 separator in case NAMESPACE is not supported.

 --skipmess     reg  : Skips messages maching the regex.
                       Example: m/[\x80-ff]/ # to avoid 8bits messages.
                       --skipmess is applied before --regexmess
 --skipmess     reg  : or this one, etc.

 --pipemess     cmd  : Apply this cmd command to each message content
                       before the copy.
 --pipemess     cmd  : and this one, etc.
 --disarmreadreceipts : Disarms read receipts (host2 Exchange issue)

 --regexmess    reg  : Apply the whole regex to each message before transfer.
                       Example: s/\000/ /g # to replace null by space.
 --regexmess    reg  : and this one, etc.

 --regexflag    reg  : Apply the whole regex to each flags list.
                       Example: s/"Junk"//g # to remove "Junk" flag.
 --regexflag    reg  : and this one, etc.

 --delete            : Deletes messages on host1 server after a successful
                       transfer. Option --delete has the following behavior:
                       it marks messages as deleted with the IMAP flag
                       \Deleted, then messages are really deleted with an
                       EXPUNGE IMAP command.

 --delete2           : Delete messages in host2 that are not in
                       host1 server. Useful for backup or pre-sync.
 --delete2duplicates : Delete messages in host2 that are duplicates.
                       Works only without --useuid since duplicates are
                       detected with an header part of each message.

 --delete2folders    : Delete folders in host2 that are not in host1 server.
                       For safety, first try it like this (it is safe):
                       --delete2folders --dry --justfolders --nofoldersizes
 --delete2foldersonly   reg : Deleted only folders matching regex.
                              Example: --delete2foldersonly "/^Junk$|^INBOX.Junk$/"
 --delete2foldersbutnot reg : Do not delete folders matching regex.
                              Example: --delete2foldersbutnot "/Tasks$|Contacts$|Foo$/"
 --noexpunge         : Do not expunge messages on host1.
                       Expunge really deletes messages marked deleted.
                       Expunge is made at the beginning, on host1 only.
                       Newly transferred messages are also expunged if
                       option --delete is given.
                       No expunge is done on host2 account (unless --expunge2)
 --expunge1          : Expunge messages on host1 after messages transfer.
 --expunge2          : Expunge messages on host2 after messages transfer.
 --uidexpunge2       : uidexpunge messages on the host2 account
                       that are not on the host1 account, requires --delete2
 --nomixfolders      : Avoid merging folders that are considered different on
                       host1 but the same on destination host2 because of
                       case sensitivities and insensitivities.

 --syncinternaldates : Sets the internal dates on host2 same as host1.
                       Turned on by default. Internal date is the date
                       a message arrived on a host (mtime).
 --idatefromheader   : Sets the internal dates on host2 same as the
                       "Date:" headers.

 --maxsize      int  : Skip messages larger  (or equal) than  int  bytes
 --minsize      int  : Skip messages smaller (or equal) than  int  bytes
 --maxage       int  : Skip messages older than  int  days.
                       final stats (skipped) dont count older messages
                       see also --minage
 --minage       int  : Skip messages newer than  int  days.
                       final stats (skipped) dont count newer messages
                       You can do (+ are the messages selected):
                       past|----maxage+++++minage---->now (intersection)
                       past|++++minage-----maxage++++>now (union)

 --search       str  : Selects only messages returned by this IMAP SEARCH
                       command. Applied on both sides.
 --search1      str  : Same as --search for selecting host1 messages only.
 --search2      str  : Same as --search for selecting host2 messages only.
                       --search CRIT equals --search1 CRIT --search2 CRIT

 --exitwhenover int  : Stop syncing when total bytes transferred reached.
                       Gmail per day allows
                       2500000000 = 2.5 GB downloaded from Gmail as host2
                        500000000 = 500 MB uploaded to Gmail as host1.

 --maxlinelength int : skip messages with a line length longer than  int  bytes.
                       RFC 2822 says it must be no more than 1000 bytes.

 --useheader    str  : Use this header to compare messages on both sides.
                       Ex: Message-ID or Subject or Date.
 --useheader    str    and this one, etc.

 --subscribed        : Transfers subscribed folders.
 --subscribe         : Subscribe to the folders transferred on the
                       host2 that are subscribed on host1. On by default.
 --subscribeall      : Subscribe to the folders transferred on the
                       host2 even if they are not subscribed on host1.

 --nofoldersizes     : Do not calculate the size of each folder in bytes
                       and message counts. Default is to calculate them.
 --nofoldersizesatend: Do not calculate the size of each folder in bytes
                       and message counts at the end. Default is on.
 --justfoldersizes   : Exit after having printed the folder sizes.

 --syncacls          : Synchronises acls (Access Control Lists).
 --nosyncacls        : Does not synchronize acls. This is the default.
                       Acls in IMAP are not standardized, be careful.

 --usecache          : Use cache to speedup.
 --nousecache        : Do not use cache. Caveat: --useuid --nousecache creates
                       duplicates on multiple runs.
 --useuid            : Use uid instead of header as a criterium to recognize
                       messages. Option --usecache is then implied unless
                       --nousecache is used. 

 --debug             : Debug mode.
 --debugfolders      : Debug mode for the folders part only.
 --debugcontent      : Debug content of the messages transfered. Huge ouput.
 --debugflags        : Debug mode for flags.
 --debugimap1        : IMAP debug mode for host1. Very verbose.
 --debugimap2        : IMAP debug mode for host2. Very verbose.
 --debugimap         : IMAP debug mode for host1 and host2.
 --debugmemory       : Debug mode showing memory consumption after each copy.

 --errorsmax     int : Exit when int number of errors is reached. Default is 50.

 --tests             : Run local non-regression tests. Exit code 0 means all ok.
 --testslive         : Run a live test with imap server.
                       Useful to check the basics. Needs internet connexion.

 --version           : Print only software version.
 --noreleasecheck    : Do not check for new imapsync release (a http request).
 --releasecheck      : Check for new imapsync release (a http request).
 --noid              : Do not send/receive ID command to imap servers.
 --justconnect       : Just connect to both servers and print useful
                       information. Need only --host1 and --host2 options.
 --justlogin         : Just login to both host1 and host2 with users
                       credentials, then exit.
 --justfolders       : Do only things about folders (ignore messages).

 --help              : print this help.

 To synchronize the source imap account
   "test1" on server "" with password "secret1"
 to the destination imap account
   "test2" on server "" with password "secret2"
 imapsync \
    --host1 --user1 test1 --password1 secret1 \
    --host2 --user2 test2 --password2 secret2


Imapsync command is a tool allowing incremental and recursive imap transfers from one mailbox to another.

By default all folders are transferred, recursively, all possible flags (\Seen \Answered \Flagged etc.) are synced too.

We sometimes need to transfer mailboxes from one imap server to another. This is called migration.

Imapsync reduces the amount of data transferred by not transferring a given message if it resides already on both sides. Same specific headers and the transfer is done only once; taken into account are by default Message-Id and Received header lines. All flags are preserved, unread will stay unread, read will stay read, deleted will stay deleted. You can stop the transfer at any time and restart it later, imapsync works well with bad connections and interruptions.

You can decide to delete the messages from the source mailbox after a successful transfer, it can be a good feature when migrating live mailboxes since messages will be only on one side. In that case, use the --delete option. Option --delete implies also option --expunge so all messages marked deleted on host1 will be really deleted. (you can use --noexpunge to avoid this but I don’t see any good real world scenario for the combination --delete --noexpunge).

A different scenario is synchronizing a mailbox B from another mailbox A in case you just want to keep a live copy of A in B. In that case --delete2 has to be used, it deletes messages in host2 folder B that are not in host1 folder A. If you also need to destroy host2 folders that are not in host1 then use --delete2folders (see also --delete2foldersonly and --delete2foldersbutnot).

Imapsync is not adequate for maintaining two active imap accounts in synchronization when the user plays independently on both sides. Use offlineimap (written by John Goerzen) or mbsync (written by Michael R. Elkins) for 2 ways synchronizations.


To get a description of each option just invoke:


or read


I wrote imapsync because an enterprise (basystemes) paid me to install a new imap server without losing huge old mailboxes located on a far away remote imap server accessible by a low bandwidth link. The tool imapcp (written in python) could not help me because I had to verify every mailbox was well transferred and delete it after a good transfer. imapsync started its life as a patch. The tool comes from the Mail-IMAPClient-2.1.3 perl module tarball source (in the examples/ directory of the tarball).


While working on imapsync parameters please run imapsync in dry mode (no modification induced) with the --dry option. Nothing bad can be done this way.

To synchronize the imap account buddy (with password secret1) on host to the imap account max (with password secret2) on host

 imapsync --host1  --user1 buddy --password1 secret1 \
          --host2 --user2 max   --password2 secret2

Then you will have max’s mailbox updated from buddy’s mailbox.


You can use --passfile1 instead of --password1 to give the password since it is safer. With --password1 option any user on your host can see the password by using the ’ps auxwwww’ command. Using a variable (like $PASSWORD1) is also dangerous because of the ’ps auxwwwwe’ command. So, saving the password in a well protected file (600 or rw-------) is the best solution.

imasync is not totally protected against sniffers on the network since passwords may be transferred in plain text if CRAM-MD5 is not supported by your imap servers. Use --ssl1 (or --tls1) and --ssl2 (or --tls2) to enable encryption on host1 and host2.

You may authenticate as one user (typically an admin user), but be authorized as someone else, which means you don’t need to know every user’s personal password. Specify --authuser1 adminuser to enable this on host1. In this case, --authmech1 PLAIN will be used by default since it is the only way to go for now. So don’t use --authmech1 SOMETHING with --authuser1 adminuser, it will not work. Same behavior with the --authuser2 option. Authenticate with an admin account must be supported by your imap server to work with imapsync.

When working on Sun/iPlanet/Netscape IMAP servers you must use --proxyauth1 to enable administrative user to masquerade as another user. Can also be used on destination server with --proxyauth2

You can authenticate with OAUTH when transfering from Google Apps. The consumer key will be the domain part of the --user, and the --password will be used as the consumer secret. It does not work with Google Apps free edition.


imapsync will exit with a 0 status (return code) if everything went good. Otherwise, it exits with a non-zero status.

So if you have an unreliable internet connection, you can use this loop in a Bourne shell:

        while ! imapsync ...; do
              echo imapsync not complete


imapsync is free, open, public but not always gratis software cover by the NOLIMIT Public License. See the LICENSE file included in the distribution or just read this simple sentence as it is the licence text: No limit to do anything with this work and this license.


The public mailing-list may be the best way to get free support.

To write on the mailing-list, the address is: <>

To subscribe, send any message (even empty) to: <> then just reply to the confirmation message.

To unsubscribe, send a message to: <>

To contact the person in charge for the list: <>

The list archives are available at: So consider that the list is public, anyone can see your post. Use a pseudonym or do not post to this list if you want to stay private.

Thank you for your participation.


Gilles LAMIRAL <>

Feedback good or bad is very often welcome.

Gilles LAMIRAL earns his living by writing, installing, configuring and teaching free, open and often gratis softwares. It used to be always gratis but now it is often because imapsync is sold by its author, a good way to stay maintening and supporting free open public softwares (see the license) over decades.


Help me to help you: follow the following guidelines.

Report any bugs or feature requests to the public mailing-list or to the author.

Before reporting bugs, read the FAQ, the README and the TODO files.

Upgrade to last imapsync release, maybe the bug is already fixed.

Upgrade to last Mail-IMAPClient Perl module. maybe the bug is already fixed there.

Make a good title with word imapsync in it (my spam filters won’t filter it), Try to write an email title with more words than just imapsync or problem, a good title is made of keywords summary, but not too long (one visible line).

Help us to help you: in your report, please include:

 - imapsync version.

 - output near the first failures, a few lines before is good to get the context
   of the issue. First failures messages are often more significant than
   the last ones.

 - if the issue is always related to the same messages, include the output
   with --debug --debugimap, near the failure point. For example,
   Isolate a buggy message or two in a folder BUG and use

     imapsync ... --folder BUG --debug --debugimap

 - imap server softwares on both sides and their version number.

 - imapsync with all the options you use,  the full command line
   you use (except the passwords of course).

 - version.

 - the run context. Do you run imapsync.exe, a unix binary
   or the perl script imapsync.

 - operating system running imapsync.

 - virtual software context (vmware, xen etc.)

 - operating systems on both sides and the third side in case
   you run imapsync on a foreign host from the both.

Most of those values can be found as a copy/paste at the begining of the output, so a carbon copy of the output is a very easy and very good debug report for me.

One time in your life, read the paper How To Ask Questions The Smart Way and then forget it.




Pay special attention to options --subscribed --subscribe --delete --delete2 --delete2folders --maxage --minage --maxsize --useuid --usecache

If you have many mailboxes to migrate think about a little shell program. Write a file called file.txt (for example) containing users and passwords. The separator used in this example is ’;’

The file.txt file contains:

user001_1;password001_1;user001_2;password001_2 user002_1;password002_1;user002_2;password002_2 user003_1;password003_1;user003_2;password003_2 user004_1;password004_1;user004_2;password004_2 user005_1;password005_1;user005_2;password005_2 ...

On Unix the shell program can be:

 { while IFS=; read  u1 p1 u2 p2; do
        imapsync --host1 --user1 "$u1" --password1 "$p1" \
                 --host2 --user2 "$u2" --password2 "$p2" ...
 done ; } < file.txt

On Windows the batch program can be:

  FOR /F "tokens=1,2,3,4 delims=; eol=#" %%G IN (file.txt) DO imapsync ^
  --host1 --user1 %%G --password1 %%H ^
  --host2 --user2 %%I --password2 %%J ...

The ... have to be replaced by nothing or any imapsync option. Welcome in shell programming !

You will find already written scripts at


Feel free to hack imapsync as the NOLIMIT license permits it.


Entries for imapsync:


  imap_tools    :
  offlineimap   :
  mbsync        :
  mailsync      :
  mailutil      :
                  part of the UW IMAP tookit.
  imaprepl      :
  imapcopy      :
  migrationtool :
  imapmigrate   :
                  see also file W/tools/wonko_ruby_imapsync
  exchange-away :
  pop2imap      :

Feedback (good or bad) will often be welcome.

$Id: imapsync,v 1.678 2016/01/21 19:47:02 gilles Exp gilles $

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