ImprovMX

ImprovMX is an email forwarding service that lets you receive emails in your custom domain and forward them to your personal address.

Codes

450 · 550 · 551

450
450 4.2.1 Please try again later. (#id-5.9.4)

Their anti-spam check failed. We need the sender to retry sending.

550
550 5.7.1 Message considered as SPAM

Your email scored above the spam threshold and was rejected. Revise your email for any unwanted content prior to resending.

550 5.1.1 The email account you tried to reach does not exist. Please double-check the recipient's email address for typos or unnecessary spaces.
550 5.1.3 Relay not permitted. (#id-5.9.2)

The domain was not found in their system, or was not added correctly, so they can't route emails.

551
551 5.7.1 Due to the very low reputation of the sending domain, this message has been blocked (Code 2).

Your domain is on a reputation blacklist such as the Spamhaus DBL. You will need to be delisted before you can send emails.

551 5.7.1 Loop detected: Email is sent and forwarded from/to improvmx.com. (#id-5.9.0)

The destination mailbox loops back to ImprovMX. They block these messages in order to avoid loops.

551 5.7.1 Domain not found (#id-5.9.2)

The domain was not found in the ImprovMX database.

551 5.7.1 Our database returned invalid pieces of information about the requested recipient’s domain (#id-5.9.3)
551 5.7.1 Unable to correctly read the forwarding recipient (where to forward the email to) (#id-5.9.5)