[Solved] certificate verification failed for untrusted issuer /OU=GlobalSign Root CA

Error:-

Nov 11 17:09:43 server postfix/smtp[30572]: certificate verification failed for aspmx.l.google.com[74.125.200.26]:25: untrusted issuer /OU=GlobalSign Root CA – R2/O=GlobalSign/CN=GlobalSign
Nov 11 17:14:31 server postfix/smtp[3332]: certificate verification failed for in.hes.trendmicro.com[54.219.191.21]:25: untrusted issuer /C=BE/O=GlobalSign nv-sa/OU=Root CA/CN=GlobalSign Root CA
Nov 11 17:19:32 server postfix/smtp[5333]: certificate verification failed for mx6.mail.icloud.com[17.133.229.15]:25: untrusted issuer /C=US/O=GeoTrust Inc./CN=GeoTrust Global CA
Nov 11 17:19:35 server postfix/smtp[5333]: certificate verification failed for mx5.mail.icloud.com[17.133.229.14]:25: untrusted issuer /C=US/O=GeoTrust Inc./CN=GeoTrust Global CA

Solution:-

You need to mention the SSL CA file path, For me it was letsencrypt SSL and i gave it the complete chain, It worked.
Added below line in /etc/postfix/main.cf and restarted postfix

smtp_tls_CAfile = /etc/letsencrypt/live/the-d2.com/fullchain.pem

service postfix restart