# eM Client 11 – Simple MAPI not working with 32-bit Subiekt GT

**URL:** <https://forum.emclient.com/t/em-client-11-simple-mapi-not-working-with-32-bit-subiekt-gt/119833>\
**Category:** Mail\
**Created:** [October 19, 2026, 8:50am UTC](https://forum.emclient.com/t/em-client-11-simple-mapi-not-working-with-32-bit-subiekt-gt/119833 "2026-10-19T08:50:27Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Klaudiuzs](https://forum.emclient.com/user_avatar/forum.emclient.com/klaudiuzs/32/20505_2.png) [@Klaudiuzs](https://forum.emclient.com/u/Klaudiuzs)\
**Post date:** [October 19, 2026, 8:50am UTC](https://forum.emclient.com/t/em-client-11-simple-mapi-not-working-with-32-bit-subiekt-gt/119833/1 "2026-10-19T08:50:27Z")

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Hello,

After updating from eM Client 10 to eM Client 11.0.1201 (MSIX x64), Simple MAPI integration with Subiekt GT (32-bit accounting software) stopped working.

The integration worked correctly with eM Client 10.

**We have identified two problems:**

**1. When the default mail client is set to “eM Client”:**

Subiekt GT displays the error:

“Either there is no default mail client or the current mail client cannot fulfill the messaging request.”

The registry points to `C:\Program Files (x86)\eM Client\MailClient.Mapi.dll` , but this file no longer exists.

**2. When the default mail client is set to “PackagedMail”:**

The Outlook error disappears, but the email composition window does not open.

Instead, Windows continuously creates `MmgaServer.exe` processes. During testing, more than 6,000 processes accumulated.

Interestingly, after changing the default client back to “eM Client”, the pending message sometimes opens correctly, including the recipient, subject and attached PDF invoice. The number of new processes then stops increasing.

**Additional information:**

- Windows 11
- eM Client 11.0.1201, MSIX x64
- Subiekt GT, 32-bit
- `AlwaysUseLegacyMapiRegistration = 1` is already enabled
- Repairing and reinstalling eM Client 11 did not resolve the problem
- No newer updates are available

**My questions:**

Is this a known issue with eM Client 11 and 32-bit Simple MAPI applications?

Is there an official fix that restores integration with Subiekt GT without downgrading to eM Client 10?

Could you please provide instructions for repairing the MAPI registration?

Thank you for your assistance.

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**Author:** ![cyberzork](https://forum.emclient.com/user_avatar/forum.emclient.com/cyberzork/32/9734_2.png) [@cyberzork](https://forum.emclient.com/u/cyberzork)\
**Post date:** [October 19, 2026, 10:12am UTC](https://forum.emclient.com/t/em-client-11-simple-mapi-not-working-with-32-bit-subiekt-gt/119833/2 "2026-10-19T10:12:39Z")

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This post by @Filip_Navara might help you

> [@System-wide Simple MAPI failure with eM Client Pro on Windows 11](https://forum.emclient.com/t/system-wide-simple-mapi-failure-with-em-client-pro-on-windows-11/119261/2):
>
> The new eM Client 11 MSIX packages use system support for redirecting Simple MAPI calls into packaged applications. The relevant registry keys are these ones: Neither HKLM\SOFTWARE\Clients\Mail\eM Client nor HKLM\SOFTWARE\WOW6432Node\Clients\Mail\eM Client is relevant anymore. .mapimail is not in any way related and it’s not our registry keys. I cannot really advise what to check next. The default value in HKEY\_LOCAL\_MACHINE\SOFTWARE\Clients\Mail should be PackagedMail. The default …