Services for the infrequent secure file transfer from tenants

[Svend W.]

Any recommendations on inexpensive and user-friendly solutions for the occasional secure file transfer from applicants and tenants? 

In my case, it's mainly for getting a picture of any Social Security Cards before signing the lease electronically, so it's pretty infrequent. Wouldn't want the tenant to send that to me by email or SMS due to identity theft concerns, but would also prefer not to do tech support on the ins and outs of file sharing with Dropbox or whatever.

Thanks.