Blocs doesn’t use the Formmail script as standard. - it has it’s own built in script. Formmail is a third party script by Tectite, which actually works very well with Blocs. As far as I am aware the standard built-in script uses the normal sendmail function of PHP. If your host is no longer supporting this function, you may have to look for a new host.
It would be unusual for a hosting company to restrict your use of PHP scripts as many websites rely heavily on such scripts, not only for form processing but for a wide range of e-commerce applications.
If you wish to use an alternative script in blocs, it’s very simple to do. Just select your form and change the settings from self Hosted to Custom (see screenshot below). You can then add the URL of your chosen form script. This would have to be installed on your server before it will function - it needs you to do nothing else in Blocs.