Workmail error 0x80040201

I'm having the same issue. I googled in and most results talk about an issue with outlook autocomplete which is not the case, but I deleted the contacts I sent the email to from my contacts and resent the message and it went through once. Then the problem came back. (Hope this helps. I also need this fixed.)

For reference here's the full response:

Unfortunately, the system was unable to deliver your mail. The error given was:

2022-02-17 16:37:58 : Conversion error: 0X80040201. No error details specified.

You may need to contact your e-mail administrator to solve this problem.

Hello,

I received an update from the service team this issue should be resolved. Thank you for reporting this.

Kind regards, Robin

I've got the same error, when changing the from address and using one that is saved in the address book. Deleting the contact and sending again, it fixes the problem.

I change the from address because I use aliases, so if my main user is admin@domain.com, and I want to send with dev@somain.com, this alias MUST not be in the address book.