Nextcloud + Davmail + Exchange incorrect attachment (.eml)


Given: Nextcloud 18.0.3 (with maill app), Davmail 5.4.0, Exchange 2013
mail arrives and leaves, there are no problems.

The problem with attachments (any format)! They are, but they are downloaded as .eml files that are empty inside. Images in the letter itself are also not displayed.

Downloading the .eml file and changing the extension to the appropriate one does not help, nothing opens then.
Through Davmail in Outlook 2007, these same files come normal, no problem.
I connected gmail to nextcloud, all attachments to nextcloud come normal, no problem.

It turns out the problem is in a bunch of Nextcloud Davmail Exchange. Moreover, Davmail and Exchange work fine together. Both Nextcloud and Gmail also work fine.

Explored the entire Internet, nothing helps, please help!

P.S. - Nextcloud maill app:
Server: Debian 10.3, nginx/1.14.2, php 7.4

I solved the problem for myself using Exchange directly bypassing Davmail. Apparently Davmail modifies the data and nextcloud mail does not know how to display it correctly.