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  1. Outlook Connectivity with MAPI over HTTP | Microsoft Community Hub

    May 9, 2014 · MAPI/HTTP increases the CPU load in the Exchange Client Access Servers. This is a 50% increase over Exchange 2013 RTM, however it is still lower than Exchange 2010 requirements. …

  2. Understanding how Outlook, CDO, MAPI, and Providers work together

    Apr 8, 2005 · CDO and Outlook are both MAPI applications, meaning that they use MAPI APIs to access their data, and therefore, the underlying providers. CDO and Outlook share a common set of …

  3. Planning considerations for REST-based (aka new model) calendar …

    Aug 12, 2022 · The REST Model The new calendar sharing model based on REST is designed to avoid MAPI issues related to conflicting permissions and multiple editing delegates. This is one of the …

  4. Issue in SendOnBehalfTo | Microsoft Community Hub

    Apr 13, 2020 · I Have a client having issue while trying to sendonbehalf email from Shared Mailbox which end user have SendOnBehalfTo permission. When he select From...

  5. Exchange 2013/2019 coexistence and client connectivity to new 2019 ...

    Apr 30, 2023 · Hey all, Some details first: Forest/Domain functional level: 2012 R2 (only one domain) 2 x Exchange 2013 CU 23 Servers in a DAG (both on Server 2012) 1 x Exchange 2019 CU 12 server …

  6. OWA Exchange 2016 Error - Something went wrong | Microsoft …

    Hi All, Trying to access to owa and receiving this error: A problem occurred while you were trying to use your mailbox. X-ClientId:...

  7. Recommendation: Enabling Kerberos Authentication for MAPI Clients

    Apr 15, 2011 · MAPI supports Kerberos authentication and the default setting in Outlook 2007 and later is to negotiate the strongest authentication available when not running in Outlook Anywhere mode. In …

  8. New Outlook: MAPI / Exchange | Microsoft Community Hub

    May 31, 2024 · I don't think microsoft will ever try to add mapi to it because mapi is a "client side" technology that whereas the new outlook is all server side (excluding the html/css rendering).

  9. Managing Large Shared Mailboxes in Exchange Online – Performance ...

    May 15, 2025 · The classic Outlook (Win32) client relies on MAPI and old-style caching behavior, which makes it less ideal for fast-paced shared mailbox environments. What we’re now considering: Should …

  10. Checklist for Troubleshooting Performance Related issues in Exchange ...

    May 31, 2016 · Some of relatively common and difficult issues we see in support are related to client connectivity to Exchange.