CNAME and SSL - How to avoid security error?


I have an application called sendy installed in the following setup:

This works fine on a Digital Ocean droplet LAMP install.

Sendy is an email platform that allows you to send emails via AmazonSES.

It has a feature to use custom domains for tracking clicks etc. You add the custom domain and then it tells you to add it as a CNAME that points to the sendy install.

For example: CNAME record pointing to

I have a wildcard SSL on which is hosted elsewhere.

However, I get security errors which I assume is some sort of name mismatch thing?

Is there something I need to do with the letsencrypt certificate on


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yes, add a valid certificate for if you cannot, remove the cname and reverse proxy the application.


in general, you can have a zone that looks like this

www in cname
blog in cname

on your server you will need valid certificates for www.yourdomain and blog.yourdomain, and it’s irrelevant if you have a valid cert for the cname destination

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Is there a guide you can point me in the direction of for doing that via certbot?

I did the intitial SSL in the command line but using a tutorial.

Not sure what string of code is required for doing that?

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certbot --dry-run -d domain_name

if this command works, remove --dry-run and run the command again.


Thanks, I just installed one for track.domain2 which worked.

But now the original has a security error.

I am guessing I overwrote something :grin:

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does the webserver you are using support multiple certificates? (both apache and nginx do)

then install both.

otherwise, use certbot --dry-run -d domain_name -d other_domain_name


Thanks I think I got it sorted. Thanks for the help and speed of replies.

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