Using email as User ID

PHPMaker v2026.8

I found out that if you use email address as your User ID, you will hit with a Symphony Cache validation error below:

Cache key "user_id.hierarchy.VIEW_USERS.myemail@email.com" contains reserved characters "{}()/\@:".

To avoid this error, I have unchecked the option “Use cache for User Level and User ID”. Is this the only way I can use, or there is a better solution?