Originally Posted by rodzok
after latest core upgrade 5.3 xcart this week....
If it's XC 126.96.36.199 to XC 188.8.131.52 (you didn't say in your post) then there's no change for us, post upgrade.
The Contact Us page sends e-mails, just at it did prior to the XC5 core upgrade.
The XC 184.108.40.206 Change Log
only lists two small changes, so it would be unlucky, if this small core upgrade did cause that issue.