We have earlier had a fully working program using IMAP and the LoginPlain method to obtaining access to a shared mail box. After our customer upgraded to Exchange 2016 it has stopped working giving us an exception saying: AUTHENTICATE failed.
We have used login sending parameters in this format:
imap.LoginPLAIN("alias", "user@domain", "pwd");
Do you know what could have happened?
Is there any changes in Exchange 2016 that can effect authentication?