Good E-Mail Delivery Returns
After 35 yrs. in the commercial hosting business, I must give smtp.com credit for support. They try really hard.

Switched to cPanel compute engine years ago.
Google blocks mail ports and you must use a 3rd party provider to deliver mail or build your own mail server somewhere else and connect with api ect.

Have time critical time sensitive mail delivery demands. Not a single bulk mail provider has acceptable mail delivery. Due to snow-shoe reputations.

Yes 3rd party delivery barely works and is not reliable. I strongly advise forgetting cPanel mail and have your clients use Google Workspace or Microsoft Protection Outlook.

Have lost tons of clients over 3rd party mail delivery.
What can you do? Sue them! not...