The emails that are generated through a contact form i created with WebForm Builder (April 2015 edition) aren't always received by one of the email recipients. When an email manages to make it through, this is received as part of the message:

"[GFI-SPAM HEADER CHECKING] -
Email has different SMTP TO: and MIME TO: fields in the email addresses"

Any suggestions as to how to fix this?

Thanks.