Hi Kim,We are experiencing that as well. Our audiences are bigger than ever, and every single participant needs to receive the email with login details.You could try sending a plain text email from CVENT. In the email designer, if you click the gear icon next to an email - you can set it to plain text only. You'll have to keep it simple as you can't style anything or hyperlink, but you can add data tags and URLs. It's not an easy thing to test either though, as reporting is saying they were delivered either way, just not opened.Also, if you haven't already you can ask customer support about DKIM which is an email authentication method, which could help here. CVENT reached out to us in April 2020 to get that upgraded and installed properly.In my opinion it's not really realistic to ask registrants to whitelist an email address. It's hard enough to get them to register!
Let me know if you come across anything else that ends up being helpful.