I also removed reject_unknown_sender_domain; then the mails come in, though some of them were then still rejected by rspamd, for similar reasons. I tweaked rspamd a bit, we’ll see; I still assume rspamd would catch actual spammers so for me removing reject_unknown_sender_domain is probably not an issue. I’m on ARM64.
Still wondering though on which side there’s an issue, maybe there’s confusion between looking up bounce.em.delhaize.be, em.delhaize.be, mta.em.delhaize.be and/or delhaize.be?
Have a look at these parts from the raw source:
Authentication-Results: mymailcowserver; dkim=temperror (“DNS error when getting key”) header.d=em.delhaize.be header.s=50dkim1 header.b=tTc3YADf; dmarc=temperror reason=“SPF/DKIM temp error” header.from=delhaize.be (policy=temperror); spf=temperror (mymailcowserver: error in processing during lookup of bounce-10_HTML-54618272-97023-510000646-918@bounce.em.delhaize.be: DNS error) smtp.mailfrom=bounce-10_HTML-54618272-97023-510000646-918@bounce.em.delhaize.be
X-Spamd-Result: default: False [-2029.43 / 16.00]; GLOBAL_MIME_FROM_WL(-2050.00)[hello@em.delhaize.be]; HFILTER_HOSTNAME_UNKNOWN(5.00)[]; BAYES_SPAM(4.48)[99.95%]; MX_MISSING(3.50)[]; HFILTER_FROMHOST_NORES_A_OR_MX(1.50)[bounce.em.delhaize.be]; DATE_IN_PAST(1.00)[48]; SUBJECT_ENDS_QUESTION(1.00)[]; URI_COUNT_ODD(1.00)[71]; HFILTER_HELO_IP_A(1.00)[mta.em.delhaize.be]; RDNS_NONE(1.00)[]; MX_INVALID(0.50)[]; MIME_GOOD(-0.40)[multipart/alternative,text/plain]; HFILTER_HELO_NORES_A_OR_MX(0.30)[mta.em.delhaize.be]; FORGED_SENDER(0.30)[hello@em.delhaize.be,bounce-10_HTML-54618272-97023-510000646-918@bounce.em.delhaize.be]; MANY_INVISIBLE_PARTS(0.30)[4]; ONCE_RECEIVED(0.10)[]; HAS_LIST_UNSUB(-0.01)[]; MIME_TRACE(0.00)[0:+,1:+,2:~]; BCC(0.00)[]; RCPT_MAILCOW_DOMAIN(0.00)[mydomain.com]; ARC_NA(0.00)[]; PREVIOUSLY_DELIVERED(0.00)[filip@mydomain]; RCPT_COUNT_ONE(0.00)[1]; DMARC_DNSFAIL(0.00)[delhaize.be : SPF/DKIM temp error,reject]; TO_DN_NONE(0.00)[]; ASN(0.00)[asn:14340, ipnet:161.71.0.0/17, country:US]; RCVD_TLS_LAST(0.00)[]; FROM_HAS_DN(0.00)[]; ARC_SIGNED(0.00)[mydomain.com:s=dkim:i=1]; R_DKIM_TEMPFAIL(0.00)[em.delhaize.be:s=50dkim1]; RCVD_COUNT_ONE(0.00)[1]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_NEQ_ENVFROM(0.00)[hello@em.delhaize.be,bounce-10_HTML-54618272-97023-510000646-918@bounce.em.delhaize.be]; R_SPF_DNSFAIL(0.00)[temporary DNS error]; DKIM_TRACE(0.00)[em.delhaize.be:?]; RDNS_DNSFAIL(0.00)[]; MISSING_XM_UA(0.00)[]
PS: separate but related question here which would help me in training rspamd better.