My company runs internal e-mail-traffic using Outlook 365. I prefer using a proper e-mail client (in my case: thunderbird) via IMAP and SMTP, which is no problem since the server adresses are provided in the Outlook 365 settings dialogue.

Now, I would also like to be able to use the contacts directory set up by the company. I presume the proper way to include such a contacts directory into thunderbird is using LDAP; however, it seems to me that there is no official LDAP address.

Is there an LDAP access to Office 365 contact directories, and where can I find its address?

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    @Appleoddity It has a bit of irony that you posted your overly emotional comment using two technologies over 25yrs old themselves, namely HTTP and HTML :). Your comment does not explain why an IMAP-setup should not be doing today what it does since 30yrs. Of course, I do not ask how to connect Thunderbird to all those Exchange-specific features.
    – Bubaya
    Dec 30, 2017 at 8:01
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    I think this is a good question. IMAP is standardized and widely supported across many platforms as well as programs, as well as SMTP. Feb 12, 2018 at 7:28
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    This is possible and the question/answer here addresses it: superuser.com/questions/801831/… Aug 12, 2018 at 0:56
  • Is this not possible yet? We'd like LDAP access to Exchange/Azure AD online for a different but similar reason - to automatically populate a list of "Scan to email" contacts on an HP printer. To prevent having to add them manually May 30, 2019 at 11:29
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    Does this answer your question? Configure Thunderbird to access Office 365 LDAP addressbook
    – harrymc
    May 2, 2020 at 8:29

1 Answer 1


LDAP is an account directory protocol.

IMAP is a mail protocol.

IMAP does not have access to the 365 global address list (GAL). Only a mail program (like Outlook) which is connected to 365 via Exchange (ActiveSync) has access to this feature.

For Thunderbird to access a shared address book, it would need a CardDAV server. Microsoft does not offer CardDAV as an option.

Outlook has been a proper email client for decades. I am sure if you gave it a chance, it would perform well for you.

If you prefer Thunderbird, you will have to go without some features. Thunderbird is a great application, but it does not support 365 ActiveSync connections and with it the advanced features it brings.

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    I assume OP was asking for LDAP precisely because it's an account directory protocol... In the past it has been possible to connect various mail clients' address books (including Thunderbird and Outlook Express) to the LDAP service that traditional Active Directory offers, to get something approximating the GAL. Jul 11, 2022 at 20:43
  • I am unaware of such things and if it did happen it would be very insecure and quickly locked down by any competent system admin. LDAP also does not work as an address book, never has and never will.
    – Derek
    Jul 11, 2022 at 21:01
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    You sure about that? It was literally created to act as an address book before AD even existed. You can use it as an address book in Microsoft Outlook. Windows used to have an "Address Book" app that had several LDAP directories built in. Jul 11, 2022 at 21:06

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