If your sending domain is correctly authenticated but your emails are still being filtered as spam when sending to internal recipients that share the same email domain as the sending domain, then whitelisting eMarketeer email servers can be done to ensure that these emails can be delivered. This may be a necessary step as when your company spam filter receives emails that use an internal From address but that actually originates from an external IP (such as eMarketeer and other email service providers) it is more likely to filter the email as spam due to the higher risk of it being fraudulent.
eMarketeer Email Servers
IP-addresses to whitelist:
220.127.116.11 18.104.22.168 22.214.171.124 126.96.36.199 188.8.131.52