Revision 72 as of 2021-08-10 14:54:06

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Migrating your mailbox from ISG to Exchange


Only follow if instructed to do so!

All these migration steps are only necessary, if your institute decided to migrate to the exchange mail server and your technical contact has told you, to follow these instructions.

Some professorships and institutes at D-ITET have decided to use the exchange mail server instead of the D-ITET mail server. This guide is intended to show you the steps to be able to move your mail account to the exchange server. If certain steps in these instructions are unclear, please contact your technical contact first or create a ticket by sending an email to <>.

Pre-migration steps

Cleanup Tasks


These Steps can be done at every time BEFORE the migration occurs!

There are some limitations on the Exchange Server which mean that not all emails can be transferred. You must have completed the following steps before you start the actual migration itself:

Mailbox Size and Mailbox Items

Thunderbid: How to see current Mailbox Size and Mailitems
  1. Press once ALT so that the Main Menu (containing File, Edit, View etc.) is shown.

  2. Then choose from the Menu View -> Layout -> Folder Pane Columns

  3. Right click with your Mouse in the Header of the Folder Pane and make sure Total and Size are selected.

  4. Collapse the whole mailaccount (by left clicking the account name) to see the summary of total mails and the used space on the server.

Outlook: How to see current Mailbox Size and Mailitems
  1. Right click on the Account name and choose Data File Properties... from the pop-up menu.

  2. In the new Window, click the Folder Size... Button. Then you can see a rough overall size (yellow marked) and the size for each folder.

  3. Each Outlook folder can be set up to show the number of total messages. Unfortunately these settings are applied on a folder by folder basis. Right click on a folder and choose Properties....

  4. Make sure you are in the General tab of the new pop-up window. There select Show total number of items and press apply. This has to be done for every folder separately!

Roundcube: How to see current Mailbox Size and Mailitems
  1. Visit Our Webmail Client and login with your credentials.

  2. Roundcube can not create a summary view. Instead you have to select every folder to get ist foldersize and the amount of mails. In the left Pane click the settings button. Then choose Folders. Now you can click on every folder to see the Message Amount. To also see the size of that folder, click Click to get folder size.

Individual Mails bigger 20MB

Thunderbird: Find emails bigger 20MB
  1. While Thunderbird is open, press CTRL-SHIFT-F or select Edit -> Find -> Search Messages.

  2. Create a Rule named: Size (KB) is greater than 20480

  3. Press the Search Button to find the Mails. If you have a lot of large Mails, it could make sense to press Save as Search Folder. In that case a virtual Folder will be created containing all large emails.

Outlook: Find emails bigger 20MB
  1. On the Menu pane choose Folder.

  2. Click the New Search Folder Button.

  3. In the new pop-up Window, scroll down to Organizing Mail and select Large Mails

  4. Select the Choose... Button and then enter 20480

Roundcube: Find emails bigger 20MB
  1. Since the default Theme Elastic does not have sorting fields, you need to switch to the Classic Theme. In the left Pane click the settings button. Then choose Preferences and User Interface and finally select Classic.

  2. Click the blue Save Button.

  3. Click the Mail Icon to get back to your mails and folders.

  4. For each folder you need now to select the specifiy folder in the left Folder pan. Then select the Filter With attachment to only show files with attachments and finaly click on size to show the biggest files on top.

Forward Management


Please do only carry out the following steps one day before or on the day of the migration at the earliest.

Remove any IAM forward

Before the account can be migrated, you may have to delete existing forwards on the exchange server and set up new forwards on the ISG mail server. These forwards are necessary in order to receive the mails on the exchange server until the final changeover of the domain to the exchange server.

By default we set a forward on the exchange server so that you would not miss any mail sent to your IAM account directly. This forward needs to be removed. To do so execute the following steps:

  1. visit

  2. Login with your username and password

  3. Click Self Service and Manage forward to adjust your forward settings.

  4. Remove any content in the Recipient Field and make sure Save and forward mails is not set. Then click Save.

Set a forward on the ISG mailserver

After removing the IAM forward you need to set a forward to the exchange server. The simplest way to do so is by using roundcube:

  1. Visit

  2. Login with your username and password

  3. Select Settings and then Filters

  4. By default you would see the isgdefault Filter set. This set contains the two rules Deduplicate and Vacation. Click the Create Button in the upper right frame and create a sieve rule like in the picture. Replace username in the action field with your username. Afterwards click Save.


From this moment on, every incoming email will be redirected to the exchange server. To be able to read any new email you either need to login with your credentials at the exchange webinterface or you need to configure a mail client to access the exchange server. If you used thunderbird on our server you should switch to Microsoft Outlook to access the exchange mailserver to use all supported feautres (calendar etc.) Please refer to the Instructions / FAQ / How To / Tips Section on the ETH Mailbox Service Website to find instructions on how to configure a mail client to use the exchange mailserver.

Prepare an SSH-Client


This step is only necessary at the day of migration. But you could preconfigure e.g. PuTTy beforehand.

Prepare an SSH-Client like openssh (linux/mac) or PuTTy (windows) to be able to carry out the synchronization with the assigned credentials (visible on the migration day in the Migration webinterface).

configuring PuTTy on Windows

  1. On our managed machines you should find PuTTy in the list of applications or by clicking the Windows Button in the left bottom frame and typing putty. If you are using a self managed machine install PuTTy from .

  2. PuTTy opens a pop-up window. In the Basic Settings make sure to add into the Hostname line, the port is set to 22 and the Connection Type is SSH.

  3. Select the Window Category on the left side and make sure to use 150 for Columns and 50 for Rows.

  4. Select Window/Translation Category on the left side and make sure to use ISO-8859-1:1998 (Latin-1, West Europe) for the Remote character set.

  5. Click Open on the bottom of the pop-up window to establish a connection. /!\ Do not login with your personal credentials! Use the migration credentials from the webinterface (See the next section Migration webinterface) instead! /!\

  6. If this is the first time ever you connect to, a message window like the following appears. The Window shows you the servers fingerprint in ssh-ed25519 format. If the fingerprint IS NOT 3b:b0:1a:8a:ea:0a:e5:ea:bb:9e:bb:5c:ef:24:c3:92 something REALY nasty is going on and you should not press Yes. But if the fingerprint matches, press YES to save the fingerprint in the cache (this way, you do not need to re-check this fingerprint every login again!). (More information about Fingerprints can be found in the SshFingerprints Article and the fingerprints for most of our Unix based hosts can be found here)

Using openssh on linux / mac

Open a terminal and use the following command. Replace migruser by the migration user assigned to you (as seen in the webinterface). The password can also be found in the webinterface, but only on the day of migration.


Migration webinterface

Together with the technical contact of an institute, the ISG creates a list of the users to be migrated and sets a migration date for each account. As soon as the migration begins, all users can log in with their credentials at . In this interface you can see:


  1. The accounts you need to migrate (most people will only see their own username here)
  2. The day on which your migration is planned
  3. Your migration credentials (username/password) to access the synctool. These credentials can only be seen the day your migration is planned.
  4. Link to this instruction website



Before you start the synchronisation process, make sure you have followed all Pre-migration steps!

  1. Login to the and make sure to write down the username and the password for the migration account.

  2. Open an SSH connection (Windows/Unix) and login with the credentials from the webinterface. /!\ If you have multiple accounts to migrate, you need to do these steps for every account! /!\

  3. Enter the accountname which needs to be migrated (testuser in the example). Mostly this will be your own username only ( /!\ Do not use mmigr01, mmigr02, mmigr03 or mmigr04 here!!! /!\ You need to enter the user which needs to be migrated (e.g. your username!)).

  4. Select 1 if you use the same password on both server (Applies to most users!) or 2 if you have different passwords.

    1. If you selected 1 you can enter the password.

    2. If you selected 2 you need to enter separate passwords for each mailserver
      SYNCTOOL-step03-Enter_password-ISG.png SYNCTOOL-step03-Enter_password-ID.png

  5. The credentials you entered will be checked against both servers. If everything was correct, you will be presented one of the two menus. The left one will be seen if you never migrated this account before, the right one, when you already snychronized the account and need to resync.
    SYNCTOOL-mainmenu_simple.png SYNCTOOL-mainmenu_full.png

  6. Start now to synchronize your account by choosing sync or resync. While the mail account gets synchronized, you will see the progress of the tool.


Depending on the size of your mailbox and the amount of emails, this step could take from a few minutes to a few hours!

When the sync has errors

When you have finished your synchronisation you will see this menu
You can select analyze to let the tool check for the most common (mostly harmless) errors:

  1. In the best case there were no errors at all

  2. Sometimes some mails could not be transfered because they are too large for the exchange mailserver. In that case you need to delete or export the email (see Pre-migration steps). The error will show two screens. The left gives you some information, the right one shows, which mails had the problem.
    SYNCTOOL-error_large_mails_01.png SYNCTOOL-error_large_mails_02.png

  3. When you get the message, that some folders were not selectable, do not worry. This is only an informational message and not a real error. You can ignore these messages. <<BR> SYNCTOOL-error_unselectable_folders.png

  4. If the tool finds some critical error you could try to resync. But if the same error occurs again, you should contact ISG as stated in the screenshot.

Check the logfile

When you select showlog from the mainmenu you can see the last logfile created in this session. Use it to check the created logfile by yourself.
The showlog commando is the only one, where you can scroll through the entire logfile.

Final steps

If you had no problems while syncing the data you are finished with your syncrhonisation:

If you had problems contact first your technical contact and if he can not help, inform ISG by creating a ticket. Write an email with your problem to <>.