Knowledgebase: Reflexion
5.1.0 Sender Denied
Posted by Carlos Rios on 15 November 2017 03:08 PM

"554 5.1.0 Sender Denied" means that the recipient has added your address and/or domain to their block list.

In order to resolve this particular issue, the recipient will need to check their Exchange configuration for any potential filters that could be restricting mail acceptance from the sending address.

ERROR: This domain name does not match domain registered in the license key file (, allowed domains:,localhost, please change the product path to match the domain under Admin CP > Settings > General Settings
This product will not work properly unless untill that value is changed.

For more information please contact Kayako support at