HI
I just turned on a custom email address for my domain. Contact 7 form not functioning after configuration.
Using Hostinger to host
What’s the error code?
Do you get some error in the Console of the Developer Tools (F12) at your Web browser? 
I wonder if, could you double-check for some possible challenged/blocked firewall events in the firewall events if you navigate to the Cloudflare dashboard → Security → Overview and lookup for Firewall events for the past 24hours or so. Once you find them, click on a particular one to find more details about it (user-agent, IP, HTTP version …). If yes, could you share some details which service was triggered that blocked you?
- you should see your origin host/server IP out there and user-agent like WP-cron or WordPress/version
Just in case if you encouter some issues and/or errors, since it’s related to the WordPress, I’d suggest you to allowlist your origin host / server / hosting IP address by navigating to the Security → WAF → Tools → IP Access Rules with the action “allow” for your Website and try again.
It knows to happen due to the WordPress using HTTP/1.0 and empty user-agent, therefore while executing WP-Cron or some other related JSON/REST API request via plugin which triggers the WAF rules (as it should normally).
Otherwise, you could try to disable the Rocket Loader and/or Auto Minify (HTML, CSS, JS) which could somehow have an impact, if so, but I doubt (should be rather some cache).
Rather, could be Ajax then and some Bot Fight Mode or Browser Integrity Check or JS minimization.
It is now working after configuring Sendinblue SMTP Mail.
2 Likes
May I ask if you’r A mail DNS record, or rather the hostname used for MX record is proxied and 
?
Kindly, double-check by looking into the article from below.