Thank you for the quick response. In the end we needed to apply a bunch of tricks and patch the broken header to create a valid ARC signature that was accepted by Microsoft again: https://gitlab.com/fumail/fuglu/-/blob/2b3412caf0c811d0d33186487cd8761b9830901c/fuglu/src/fuglu/plugins/domainauth.py#L302
-> problem solved!
Thank you for the quick response. In the end we needed to apply a bunch of tricks and patch the broken header to create a valid ARC signature that was accepted by Microsoft again: /gitlab. com/fumail/ fuglu/- /blob/2b3412caf 0c811d0d3318648 7cd8761b9830901 c/fuglu/ src/fuglu/ plugins/ domainauth. py#L302
https:/
-> problem solved!