This post is specific to using a certain app, but has this handy chart of some common email clients and their anchor tag support. It is super spotty and I don’t know that it’s a good idea to design an email around expecting them to work, even if constructed properly.
Even when supported, many clients have slightly different expected anchor formats that are and are not supported, so might require custom scripted anchors that are different than what MultiMarkdown would generate.
Not impossible they could be useful, but certainly might have inconsistent results for the people receiving your emails.