Setup of Comodo PositiveSSL certificates on Postfix/Dovecot

Suppose that is my mail server.

I have the following files:
*, created on my linode (along with which is submitted to Namecheap when purchasing Comodo PositiveSSL)

  • Comodo gives me back these files: AddTrustExternalCARoot.crt, PositiveSSLCA2.crt, and platoexamplecom.crt
    What is the proper way of setting up Postfix and Dovecot using all these files?


I am a bit confused because on Nginx (if is going to be a web site), I have to cat three files together:

cat plato_example_com.crt PositiveSSLCA2.crt AddTrustExternalCARoot.crt >

Then I set it up like this:

ssl_certificate /etc/whatever/;
ssl_certificate_key /etc/whatever/;

Do I have to cat files together in a similar way for Postfix and Dovecot?

1 Reply


Do I have to cat files together in a similar way for Postfix and Dovecot?
Yes, you do it exactly the same way as nginx. (In my experience, most server programs work that way, although I have encountered a few that require the intermediate/chain certs[1] to go in a separate file.)

Relevant documentation for Dovecot and Postfix: … rtificates"> and … _cert_file">

[1] platoexamplecom.crt is your certificate, and the others are known as "intermediate" or "chain" certificates.


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