The mail server running the gnupg development lists is misconfigured, it rejects on missing SPF record.
2024-03-09 05:41:06 1ripS5-00000004JwC-2A9A ** gcrypt-devel@gnupg.org R=dnslookup T=remote_smtp H=ellsberg.gnupg.com [176.9.119.14] X=TLS1.3:ECDHE_SECP256R1ECDSA_SECP384R1_SHA384AES_256_GCM:256 CV=yes DN="CN=ellsberg.gnupg.com": SMTP error from remote mail server after MAIL FROM:<XXXXXXXXX> SIZE=2443: 550 [SPF] 31.15.64.248 is not allowed to send mail from bebt.de.