As a way to maintain security Infusionsoft implemented validation on what file types would be allowed to be uploaded. Here is another post about the supported file types: File upload accepted extensions - #5 by bradb
That being said I know that other people have uploaded a file onto their server and referenced it in an email. The url would then have people download it. It isn’t as good as simply opening the file however it does have better inbox placement then an email with vcf file attachments generally.