Most of the time this is due the fact that the From address used in iWelcome emails, doesn’t have an spf record set in the customers DNS.

The settings the customer must set in DNS:
- If a record exists, the customer needs to add to the line.
- If a record does not exist, the customer can create a TXT record like this:v=spf1 -all

Common practice: customers create a separate sub domain for receiving emails and add this to their DNS record. iWelcome can also facilitate DKIM as addition.