It appears the cert does have a SAN entry. (34.160.13.42 is an IP for smtp.mailgun.org.)
$ openssl s_client -starttls smtp -connect 34.160.13.42:587 2>/dev/null | openssl x509 -noout -text X509v3 Subject Alternative Name: DNS:*.mailgun.org, DNS:mailgun.org I'm running Exim version 4.95 (in a Alpine Linux v3.16 container.) Here's a few surrounding log lines: SSL_connect: SSLv3/TLS read server hello SSL_connect: TLSv1.3 read encrypted extensions SSL verify ok: depth=2 SN=/C=US/O=DigiCert Inc/OU= www.digicert.com/CN=DigiCert Global Root G2 SSL verify ok: depth=1 SN=/C=US/O=DigiCert Inc/CN=DigiCert Global G2 TLS RSA SHA256 2020 CA1 LOG: MAIN [34.160.13.42] SSL verify error: certificate name mismatch: DN="/C=US/ST=Texas/L=San Antonio/O=MAILGUN TECHNOLOGIES, INC/CN=*. mailgun.org" H="smtp.mailgun.com" SSL verify name failure overridden (host in tls_try_verify_hosts) SSL verify ok: depth=0 SN=/C=US/ST=Texas/L=San Antonio/O=MAILGUN TECHNOLOGIES, INC/CN=*.mailgun.org SSL_connect: SSLv3/TLS read server certificate SSL_connect: TLSv1.3 read server certificate verify I have a layman's understanding of SSL certs so apologies for any naivety :) Thanks! Lance -- ## List details at https://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/