warning: TLS library problem:

[bill1977]

when I try to send mail to my mail server from Espo, I get this error.

warning: TLS library problem: error:14094418:SSL routines:SSL3_READ_BYTES:tlsv1 alert unknown ca:s3_pkt.c:1153:SSL alert number 48:


Has anyone seen this?

[AlexAv]

This is a Postfix issue

  postfix/smtpd[18426]: warning: TLS library problem: error:14094418:SSL routines:SSL3_READ_BYTES:tlsv1 alert unknown ca:s3_pkt.c:1293:SSL alert number 

Please show the main.cf and master.cf files

[bill1977]

It is a docker deployment. Here is main.cf

[bill1977]

and master.cf

[AlexAv]

The problem in SSL certificate, it need to be signed by CA. Fails to verify peer certificate because unknown CA.
In version PHP 5.6 - 7.1 SSL checking is required but you can disable checking in config.