Email Notifications via method "$NX_ROOT/bin/smtp_mail" will not be delivered, if a German Umlaut (äöü) is in the Subject.
The contact will get a mail returned with the ERROR message:
SMTPUTF8 is required, but was not offered by host MAILSERVER1
Setting smtputf8 to disabled in the sendmail does not help, because it removes all Umlauts in subject and body, umlauts in the message body are fine.
Release : 17.3.x
Component : SDM - In-bound/Out-bound Mail
Mail server is not setup for SMTPUTF8
The receiving mail server needs to be configured to accept the SMTPUTF8 subject header.