The StarLeaf Cloud delivers emails on your behalf. For example, guest invites and scheduled conference invites. For this purpose, StarLeaf uses a service called SendGrid.

Sometimes, genuine mail delivery can be hampered by over-enthusiastic spam blockers. The solution to this is to specifically allow mail from particular IP addresses. Your email admin (or sometimes, your ISP) can add rules to always allow all incoming mail from specific IP addresses. This is known as whitelisting.

The SendGrid IP address is 167.89.9.50.