When I send an e-mail /var/log/maillog (sendmail) reports: Dec 5 08:56:54 mydomain sm-mta[30576]: STARTTLS=client, error: SSL_CTX_use_certificate_file(/etc/ssl/certs/server.csr) failed Dec 5 08:56:54 mydomain sm-mta[30576]: STARTTLS=client, error: SSL_CTX_check_private_key failed(/etc/ssl/certs/server.key): 0 Dec 5 08:56:54 mydomain sm-mta[30576]: STARTTLS=client, error: load verify locs /etc/ssl/certs/, /etc/ssl/certs/server.csr failed: 0 Dec 5 08:56:54 mydomain sm-mta[30576]: STARTTLS=client, relay=smtp.gmail.com., version=TLSv1.3, verify=FAIL, cipher=TLS_AES_256_GCM_SHA384, bits=256/256 The messages go through. I use a certificate issued by gmail - if it's invalid I can't pick up mail with POP. russell bell