Yes literally it threw an invoice from AWS into spam recently. Regularly throws financial docs into spam. Like you, i have a problem with false positives not false negatives.

I brought it up with support once and the domain was failing DMARC. Headers from the AWS email that has a spam score of 9.1! I don’t know much about email but something must be wrong there on Fastmails side.

x-sieve: CMU Sieve 3.0

X-Spam-known-sender: no

X-Spam-sender-reputation: 500 (none)

X-Spam-score: 9.1

X-Spam-hits: DCC_CHECK 1.1, HEADER_FROM_DIFFERENT_DOMAINS 0.249, HTML_MESSAGE 0.001, ME_SENDERREP_NEUTRAL 0.001, MIME_HTML_ONLY 0.1, MPART_ALT_DIFF 0.724, RCVD_IN_DNSWL_NONE -0.0001, RCVD_IN_MSPIKE_H4 0.001, RCVD_IN_MSPIKE_WL 0.001, SPF_HELO_NONE 0.001, SPF_PASS -0.001, T_REMOTE_IMAGE 0.01, URIBL_DBL_ABUSE_PHISH 7, LANGUAGES en, BAYES_USED none, SA_VERSION 4.0.1

X-Spam-source: IP='54.240.9.110', Host='a9-110.smtp-out.amazonses.com', Country='US', FromHeader='com', MailFrom='com'

X-Spam-charsets: subject='UTF-8', html='UTF-8'