TLS signing error for site email links

I have a website which is sending links via email. I am using Mailgun for email and the DNS settings are managed in Cloudflare. The links are coming back with TLS signing issues (See below). Any obvious thoughts on if this is a setting or cert I need to assign in Cloudflare?

It looks like there is a failure when attempting to create a TLS session. Here is the header…???

openssl s_client -starttls smtp -connect blizzardsnowstore.com:443 -tls1_2CONNECTED(00000007)
didn’t found starttls in server response, try anyway…
140735509119944:error:140940E5:SSL routines:SSL3_READ_BYTES:ssl handshake failure:/BuildRoot/Library/Caches/com.apple.xbs/Sources/libressl/libressl-22.50.2/libressl/ssl/s3_pkt.c:895:

no peer certificate available

No client certificate CA names sent

SSL handshake has read 0 bytes and written 0 bytes

New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
Protocol : TLSv1.2
Cipher : 0000
Session-ID:
Session-ID-ctx:
Master-Key:
Start Time: 1576890351
Timeout : 7200 (sec)
Verify return code: 0 (ok)

Is this from clicking on the link that’s in the email?

Does your web server have a TLS certificate installed for your domain?

Hello,

This is from clicking an email link. I don’t have a TLS certificate, I am using LetsEncrypt on the top level domain.

Thoughts or suggestions?

…by I don’t have a TLS certificate I am saying that I don’t have it on the subdomain that Mailgun is using for SMTP.