Below is a set of sending IP ranges used for sending emails. White listing these IPs may resolve some internal deliverability issues. We strongly recommend setting up DKIM for your sending domain prior to white listing the sending IPs.
While these IP addresses don't change frequently they are subject to change without notice. Note that some of these are IP ranges not single addresses.
18.104.22.168/26 (22.214.171.124 - 126.96.36.199)
188.8.131.52/27 (184.108.40.206 - 220.127.116.11)
18.104.22.168/30 (22.214.171.124 - 126.96.36.199)