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Migrating Email, Contacts, and Calendars with Office 365

In order to move contacts and calendars from your standard webmail account into an Office 365 account, you will need to first export from webmail, then import to Office 365. This article covers both steps.

Exporting from Horde


Horde mail will need to be exported, then converted for Outlook compatibility.

Exporting Mail

  1. Login to the Horde webmail client.
  2. Right-click the folder you want to export, and choose the Export option.
    Note: If you only see the Inbox folder, click Folder Actions, and select Show All Mailboxes.
  3. Choose the Download into a MBOX File option, then click OK to begin the export.
  4. Save the file when prompted by your browser.
  5. Repeat as needed until all desired folders have been exported.

Converting Mail

  1. Download Mbox to Outlook Transfer, install, and start it.
    Important: The converter bitness should correspond to the bitness of your Outlook edition.
  2. Select the source folder where you saved *.mbox files exported from the Horde webmail.
  3. Press Scan Folder button and wait for the search to complete.
  4. Press the Save PST button.
  5. Select the folder on your computer to save the *.pst file, and specify the pst file name.
  6. Click Save, and wait for the conversion to complete.
  7. Close the Mbox to Outlook Transfer tool.


  1. Login to the Horde webmail client.
  2. Select Address Book then Import/Export.
  3. Click Export Address Book and select the export format (this must be “Comma separated values”).
  4. Select the address book to export then click Export.
  5. The .csv file containing the contact list will be downloaded locally.


  1. Login to the Horde webmail client and select Calendar.
  2. Select the 'edit' icon next to your calendar.
  3. Select the Export tab then Export ICS file. This will export the calendar to a .ics file.

Exporting from Roundcube


There is no way to export folders in Roundcube. Messages will need to be exported individually, then converted for Outlook compatibility.

Exporting Mail

  1. Login to the Roundcube webmail client.
  2. Select the email you would like to export.
  3. Click the More option, then choose Download .eml to begin the export.
  4. Repeat as needed until all desired email messages have been exported.

Converting Exported Emails into PST

Though Roundcube saves exports as a .eml, this can be converted into .pst format using a free third-party tool, EML to PST Converter. The software maintains the EML message formatting and preserves the attributes associated with the EML message. Once an email is saved in PST format, it can be imported into Office 365.


Note: Contacts from Roundcube address books are exported in the vCard format only. Office 365 does not support the import of .vcf files. The .vcf file would need to be imported to Windows and then exported to a .csv file. This can be a tedious process for many contacts, as this must be done individually for each contact.


  1. Login to the Roundcube webmail client and select Calendar.
  2. Select Export then “Export” on the popup. This will export your calendar to a .ics file.


SquirrelMail is no longer offered.


  1. Login to the SquirrelMail webmail client.
  2. Select Addresses.
  3. Select Export to CSV File. This will download the contact list as a .csv file locally.


  1. Login to the SquirrelMail webmail client.
  2. Navigate to Calendar.
  3. Select the calendar you want to export (if there are multiple calendars) then hit Export.

Importing to Office 365


Horde and RoundCube emails can be imported to Office 365; however, doing so may require the use of third-party tools.


  1. Open Microsoft Outlook.
  2. Once in Outlook, click File then Open to Open Outlook Data Fileā€¦.
  3. Select and open your new *.pst file containing emails imported from Horde webmail to begin the import.


  1. Open Microsoft Outlook.
  2. Once in Outlook, click File then Open & Export to Import/Export.
  3. Select Import from another program or file, then click the Next button.
  4. Click Browse to open your converted Roundcube mailbox in .pst format, then click Next.
  5. Choose where you are importing content to, then click Finish.


  1. Login to your Microsoft O365 account and select the People App.
  2. In order to import the .csv contact file, the option for “Try the new Outlook" will need to be toggled:
  3. Select Manage then Import Contacts, Browse and import your contact list .csv file.


  1. Login to Office 365 and select the Calendar App.
  2. On the left select Import Calendar then choose the option “From File”.
  3. Hit Browse to find your .ics file then select Import.
Wait for uploads to complete. Once finished, your webmail content should show up in your Office 365 App.
Knowledgebase Article 157,261 views bookmark tags: calendars contacts microsoft migrate office webmail

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