If your email/mail stopped working after using Cloudflare’s DNS service, it means you forgot to setup MX record for your domain. To edit your DNS zone file on Cloudflare, follow the following steps:
- Log into your Cloudflare Account and select the domain you wish to add an MX record for.
- Click on “DNS” link at the top of the page to manage your DNS settings.
- Select MX record and type your domain name in the “name” box.
- Click on “Click to configure”. It will pop up a window. Enter your mail server name (e.g. mail.example.com) and priority and then click “Save”.
- Then you need to add an A record for the mail server. Select A record and enter the name of your mail server (e.g. mail.example.com) and IP address of the server.
- After adding A and MX record for the mail server, turn them grey. It means you are not going to use CDN service for the mail server.
These steps should fix your error. If you still have the problem, it is likely that the issue is with your mail server and you should contact your mail provider for further assistance.