Setting the IMAP service to automatically enable mail files at login

User mail files must be specially enabled for IMAP use. After a mail file is enabled, Domino® converts information about each message in the mail file, such as its message ID and folder location, into a set of IMAP attributes. IMAP clients use these attributes to organize messages for display. An additional attribute informs the Router to add IMAP attributes to new messages delivered to the mail file.

About this task

When the mail conversion utility enables a mail file for IMAP use, it does not automatically add IMAP summary attributes, which enable clients to download message headers more efficiently, to messages that were already in the file before conversion occurred. To add IMAP summary attributes to preexisting messages, rerun the conversion utility manually, using the -h option.

By default, the IMAP service is set to automatically enable mail files during login. When the default setting is used, whenever a user logs in, the IMAP service checks the user's mail file to see if it is enabled. If a mail file is not currently enabled, the IMAP service provides a dedicated conversion thread to enable it. This conversion thread continues to work on this one mail file until it completes the task. If additional users require conversion services at the same time, the IMAP service provides an additional conversion thread for each instance.

Each conversion can require several minutes to complete, with conversion times for users with slow connections typically needing more time. Because the conversion threads are drawn from the same thread pool responsible for servicing other IMAP requests, a high number of conversions can place a high demand on the available IMAP resources. This can result in increased response times and service delays not only for the those whose mail files require conversion, but for other users connecting to the service as well. The likelihood of delay naturally increases if there are a large number of users accessing the server for the first time.

To prevent service delays on busy servers where many mail files require conversion, consider disabling automatic conversion during peak hours, particularly if users typically log in over a slow connection. If you disable automatic conversion, users whose mail files are not enabled for the Domino® IMAP service cannot access their mail files from an IMAP client and receive the following error message after each login attempt:

The database has not been enabled for IMAP.

When automatic conversion is not available, you must convert users' mail files manually before they can access mail from IMAP clients.

For information on manually converting mail files for IMAP access, see the related links.


  1. Make sure you already have a Configuration Settings document for the server(s) to be configured.
  2. From the Domino® Administrator, click the Configuration tab and expand the Messaging section.
  3. Click Configurations.
  4. Select the Configuration Settings document for the mail server or servers you want to restrict mail on, and click Edit Configuration.
  5. Click the IMAP > Basics tab.
  6. For the Enable IMAP during login field, choose one, and then click Save & Close:
    • Enabled - (default) The IMAP service automatically converts mail files to Domino® IMAP format the first time a user logs in from an IMAP client.
    • Disabled - Administrators must manually convert mail files for IMAP use before users can access mail from an IMAP client.