My certificate issued by StartSSL is not accepted by my clients

I have requested a new class 1 server certificate from StartSSL today and it is working great with Apache and Dovecot + (Thunderbird/Outlook/OpenXChange ), but when I try to connect to the mail server using an Apple client (Mac/iPhone), I get an SSL error message.

I have chained the

• 2_Server Certificate
• 1_Intermediate Certificate
• Root Certificate

in this order and used the resulting file as ssl_cert in dovecot. The only other two SSL settings I have are ssl=required and ssl_key = </path

Has anybody had this issue before and came up with a solution?

Solution 1:

Your problem is your CA: StartSSL.

Their certificates are nothing but a waste of electrons since this year, because Apple, Google and Mozilla don't trust them anymore out of the box and for sure others will follow.

https://linustechtips.com/main/topic/688200-apple-google-and-mozilla-disavow-wosign-and-startcom-certificates/