Forum Discussion
ARC verification fail (40) on specific Exchange Online frontends - recurring issue
Hello, We are observing recurring arc=fail (40) errors on messages forwarded through Exchange Online, caused by specific frontend servers. The same messages pass ARC verification correctly on other ...
darkglobe did you find more information on this? Asking only out of curiosity.
What tools or methods did you use to narrow down your discovery? For example were you analyzing Fiddler traces or using something different?