Users are receiving spam emails that seem to come from their own domain.
Some spam emails contain a fake 'SMTPSimple Mail Transport Protocol FROM' email address consisting of the same domain as the recipient. This may seem as if the email is coming from a local user.
Follow these steps:
1. Enable Sender Policy Framework from within SpamRazer anti-spam filter, to block emails originating from spoofed addresses. For more information refer to SpamRazer.
2. Create an SPF record for your domain. For more information refer to http://go.gfi.com/?pageid=ME_CreateSPFRecord.
3. Ensure that SpamRazer is configured to run at a higher priority than the WhitelistA list of email addresses and domains from which emails are always received module. For more information refer to Sorting anti-spam filters by priority.