[Koha] Postfix setup on ubuntu 20

[Tom Obrien]

Dear all,
I am trying to configure postfix in ubuntu 20  but I get error:
cat /etc/ssl/certs/thawte_premium_server_ca.pem | sudo tee -a
/etc/postfix/cacert.pem cat: /etc/ssl/certs/thawte_premium_server_ca.pem:
no such file or directory
when I run:

cat /etc/ssl/certs/Thawte_Premium_Server_CA.pem | sudo tee -a
/etc/postfix/cacert.pem

Can somebody advise me how I can go about this?.

Will be grateful.

Tom