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+imapsync.php is a command line tool for syncing, copying, migrating, and archiving email mailboxes between two imap servers, one way, and without duplicates.
+
+It is similar to the https://imapsync.lamiral.info/ script.
+But there are differences to cope with special IMAP extensions (like handling the METADATA and custom flags), as discussed in https://github.com/the-djmaze/snappymail/issues/419
+
+Example:
+```
+imapsync.php \
+  --host1 test1.snappymail.eu \
+  --user1 test1               \
+  --password1 "secret1"       \
+  --host2 test2.snappymail.eu \
+  --user2 test2               \
+  --password2 "secret2"
+```
+
+
+## OPTIONS
+```
+    usage: imapsync.php [options]
+
+    The standard options are the six values forming the credentials. Three
+    values on each side are needed to login into the IMAP servers. These six
+    values are a hostname, a username, and a password, two times.
+
+  OPTIONS/credentials
+
+     --host1        : Source or "from" imap server.
+     --port1        : Port to connect on host1.
+                      Optional since default ports are the
+                      well known ports imap/143 or imaps/993.
+     --user1        : User to login on host1.
+     --password1    : Password of user1.
+
+     --host2        : "destination" imap server.
+     --port2        : Port to connect on host2. Optional
+     --user2        : User to login on host2.
+     --password2    : Password of user2.
+
+    If you don't pass the user1 password via --password1 then imapsync will
+    prompt to enter the password on the terminal. Same thing for user2 password.
+
+  OPTIONS/encryption
+
+     --nossl1       : Do not use a SSL connection on host1.
+     --ssl1         : Use a SSL connection on host1. On by default if possible.
+
+     --nossl2       : Do not use a SSL connection on host2.
+     --ssl2         : Use a SSL connection on host2. On by default if possible.
+
+     --notls1       : Do not use a TLS connection on host1.
+     --tls1         : Use a TLS connection on host1. On by default if possible.
+
+     --notls2       : Do not use a TLS connection on host2.
+     --tls2         : Use a TLS connection on host2. On by default if possible.
+
+  OPTIONS/folders
+
+     --rootfolder   : prepend this name to each target folder.
+                      Like "INBOX" becomes "test.INBOX"
+
+  OPTIONS/behavior
+
+     --timeout1     : Connection timeout in seconds for host1.
+                      Default is 300 and 0 means no timeout at all.
+     --timeout2     : Connection timeout in seconds for host2.
+                      Default is 300 and 0 means no timeout at all.
+
+     --justconnect  : Just connect to both servers and print useful information.
+
+     --justlogin    : Just login to both host1 and host2 with users
+                      credentials, then exit.
+
+     --help         : print this help.
+```
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