I have been looking at the Postfix logs and wonder if this is significant:
Dec 22 10:10:08 mx32 postfix-p25/smtpd[12694]: SSL_accept:SSLv3/TLS read client hello Dec 22 10:10:08 mx32 postfix-p25/smtpd[12694]: SSL_accept:SSLv3/TLS write server hello Dec 22 10:10:08 mx32 postfix-p25/smtpd[12694]: SSL_accept:SSLv3/TLS write change cipher spec Dec 22 10:10:08 mx32 postfix-p25/smtpd[12694]: SSL_accept:TLSv1.3 write encrypted extensions Dec 22 10:10:08 mx32 postfix-p25/smtpd[12694]: SSL_accept:SSLv3/TLS write certificate Dec 22 10:10:08 mx32 postfix-p25/smtpd[12694]: SSL_accept:TLSv1.3 write server certificate verify Dec 22 10:10:08 mx32 postfix-p25/smtpd[12694]: SSL_accept:SSLv3/TLS write finished Dec 22 10:10:08 mx32 postfix-p25/smtpd[12694]: SSL_accept:TLSv1.3 early data Dec 22 10:10:08 mx32 postfix-p25/smtpd[12694]: SSL3 alert read:fatal:certificate unknown Dec 22 10:10:08 mx32 postfix-p25/smtpd[12694]: SSL_accept:error in error Dec 22 10:10:08 mx32 postfix-p25/smtpd[12694]: SSL_accept error from accounting-2.internal.harte-lyne.ca[192.168.216.88]: -1 Dec 22 10:10:08 mx32 postfix-p25/smtpd[12694]: warning: TLS library problem: error:14094416:SSL routines:ssl3_read_bytes:sslv3 alert certificate unknown:/usr/src/crypto/openssl/ssl/record/rec_layer_s3.c:1544:SSL alert number 46: It appears to me that the client is insisting on SSLv3 but that Postfix is looking for or replying with TLSv1.3. Would that cause a problem with the certificate being recognised by the client? -- *** e-Mail is NOT a SECURE channel *** Do NOT transmit sensitive data via e-Mail Unencrypted messages have no legal claim to privacy Do NOT open attachments nor follow links sent by e-Mail James B. Byrne mailto:byrn...@harte-lyne.ca Harte & Lyne Limited http://www.harte-lyne.ca 9 Brockley Drive vox: +1 905 561 1241 Hamilton, Ontario fax: +1 905 561 0757 Canada L8E 3C3