This source is known to forward email
DMARC compliance possible via SPF and DKIM.
Contact ZixCorp support for DKIM configuration. For more information on DKIM, please refer to: https://support.zixcorp.com/app/results/kw/DKIM/page/1
General SPF entry for ZixCorp is 'include:spf.zixsmbhosted.com'. For a more specific IP range, contact ZixCorp support. For more information on SPF, please refer to: https://support.zixcorp.com/app/results/kw/SPF/page/1