I’m encountering various SMTP issues using 22.214.171.124 as resolver on an email server.
In /etc/resolv.conf I have
# Generated by NetworkManager nameserver 126.96.36.199 nameserver 188.8.131.52
and this brings to very long SMTP delays (up to 25’ to send a single message, both by webmail or external client)
Just changing it to
# Generated by NetworkManager nameserver 184.108.40.206 nameserver 220.127.116.11 nameserver 18.104.22.168
everything works fine, and sending is almost immediate.
Anyone having the same issue with Cloudflare’s DNS ?