[Email Routing] "No such user here" with aliases registered

I setup several domains to do Email forwarding. Some work well, others don’t work and report “No such user here” to SMTP clients.

Example domains:
Works well:

Doesn’t work

guyjohnson.info and carriagetrailestates.org seem ro have DNS configured in the same way, so it’s unclear why they’d behave differently.

Here’s a direct quote of the error received by an SMTP client for an example alias:
SMTP Error (550): "[email protected]" (No Such User Here).

Any suggestions appreciated.

After playing around more: It may be that the email address containing a “.” character is what’s causing it to fail. That is:

[email protected] works but
[email protected] does not work.

So this is perhaps a bug, as . is a legal character in an email address per RFC822:

For example, the address:
[email protected]

is legal and does not require the local-part to be surrounded
with quotation-marks. (However, “First Last” DOES require
quoting.) The local-part of the address, when passed outside
of the mail system, within the Registry.Org domain, is
“First.Last”, again without quotation marks.

Please advise whether this can be taken on as a bug.

Still more experimentation reveals that some addresses work on some domains and some work on others and it’s not a simple pattern.

Addresses that don’t work:
[email protected]
[email protected]
[email protected]

Addresses that do work:
[email protected]
dod.us@guyjohnson.info

So back to wondering why.

Did you ever figure this issue out? I have about 12 domains using Cloudflare email routing, and half of them haven’t worked ever since I first tried the feature. Same issue as you… on the domains that are not working, I get ‘550 No Such User Here’ when I try to test the forwarding feature.

I’ve gotten no more feedback or input than you can see here, i.e. none. I haven’t tested recently, though. At least now I know it’s not just me.

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I’ve retested with the following results:
[email protected] fails with “521 5.3.0 Upstream error. bnLuqR6jnvsE”
[email protected] fails with “521 5.3.0 Upstream error. ejtl5zPFoGRs”
"Action: failed
Final-Recipient: rfc822; [email protected]
Diagnostic-Code: smtp; 521 5.3.0 Upstream error. KpjzMLC843aA
Status: 5.3.0
"
"Action: failed
Final-Recipient: rfc822; [email protected]
Diagnostic-Code: smtp; 521 5.3.0 Upstream error. 1nAiB1K88pDa
Status: 5.3.0
"

So the problem definitely remains, is fundamental to the utility of the feature, and has no known resolution. This needs the attention of the Cloudflare team.

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