After I transferred the DNS to cloudflare, my mail server can send email out smoothly but cannot receive any external emails.
What steps have you taken to resolve the issue?
I tried hard to read all the history and excluded the other possible issues. Very frustration.
I can successfully send letters to external mailboxes and get good scores at https://www.mail-tester.com/. But I just can’t receive any external letters. They will be returned at first, and then they will be lost even after they are sent.
What feature, service or problem is this related to?
Your MX record is working as you have currently set and I can connect to port 25 so you’ll need to debug your server.
It would be better if you pointed the MX record at mail.icareu.tw, create a DNS record for mail that is “DNS only” and points to your IP address. You can then proxy the A record for icareu.tw so Cloudflare features can be applied to your website traffic for the domain.
Thanks for reply. My server seems work well cuz I’ve checked it repeatedly. There are two other places that make me more doubtful：
Firewall on every internet node，Routers, NAS, or Cloudflare? Even I didn’t put any rule on them manually now.
But for Cloudflare’s firewall, I haven’t set any rules yet, but it literally means “default firewall rules”. I’m not sure if there are any rules being executed or not?
Regarding to your suggestion of mail.icareu.tw, I got it but I decided not to do it at this moment. Because the mail domain (icareu.tw) has been used widely used for a long time.
Cloudflare only proxies HTTP/HTTPS traffic (unless you use Cloudflare Spectrum) so other than for DNS, Cloudflare is not involved in your mail. DNS records for mail must be set to “DNS only”.
This doesn’t change your mail address, just the DNS record to which it points so you can proxy your web server.
Set the MX record as @MXmail
And mail A 123.195.56.181 (DNS only).
So far, I got the best result only under this setting after trying many kinds of combination. I can mail out successfully. But, when I mail to [email protected] from a gmail, I got a error message:
