WebApp e-mail delivery from Lexware faktura + order does not work

I have a customer who uses Lexware as a merchandise management system. He can not use the DeskAPP client here. The ship to the standard client does not work.
Right-click on a file and Send to works properly

Thank you for your answers

@saukatz Right-click > sendto on a file should use the same mechanism as Lexware.

Does nothing happen? Or do you get an error?

There comes an error message “The message could not be sent”

It works without problems with Outlook. Here, the mail is placed directly in the outbox. Here Lexware seems to be married to Outlook … :-(

Really bad … would have liked to use only the DeskApp


This really depends on how Lexware sends the mail. It should use the MAPISendMail(W) or MAPISendMailHelper function, but we don’t know what they do.
Do you use the same architecture for both?
I’ve seen that already with other software, where sending mails only works if DeskApp and the other application are e.g. both 32-bits.

Would also be interesting what happens with Thunderbird, because they also implement the SimpleMAPI functions.

madness … it goes with the 32bit version … Thanks for the hint.
Can be marked as solved …