Email routing delay or lost email

Hi, I setup the Email Routing service according to the tips. But I found the emails sent to my mailbox has huge delay(several hours) or didn’t arrive at all.
I just test it with this: I sent one email with the forwarding address at 10:49, and then sent another email directly to the destination email. The result is, the direct one got to the inbox within one minute, and the forwarding one still not arrive even after 30 minutes. (The sending email address and destination email address are in different domain, and both work good.)
Hope you could have a look.

A failed email with this error:

Diagnostic information for administrators:

Generating server:
Receiving server:
Total retry attempts: 28

[[email protected]]
1/13/2022 4:24:08 AM - Server at returned ‘550 5.4.300 Message expired → 421 4.4.2 Connection dropped due to SocketError’
1/13/2022 3:45:22 AM - Server at ( returned ‘421 4.4.2 Connection dropped due to SocketError’

Could you please share the domain you are using?

If you prefer I can help debug privately on Cloudflare Developers

1 Like

With sven2’s help, it looks like the delay was caused by my email provider (
After changing to another email providers, no more delays any more.