How is MXRoute ?
I'm using MXRoute since 2020. They are pretty rock-solid with good uptime.
The only issue I find is that they are too strict on IP Policy. The IPs of 3rd Party SMTP Providers are often blacklisted e.g. SendGrid & they straight discard the emails sent from them. On the other hand, Gmail doesn't discard them hence it's not possible to make everyone understand.
The filter should be more reluctant. I have also used Zoho. They were also good.
Do you have any other Hosted Email Solution ?