I've dealt with several companies, mostly banks, that use web based "secure e-mail" systems (mostly they're just file storage systems). They won't e-mail important documents to you since most people's e-mail clients use plain text and/or people use weak passwords, etc...
In fact I recently received a four inch thick stack of documentation, APIs, etc... via FedEx from a bank because they didn't trust my e-mail and I wasn't on "the list" for their "secure e-mail" site (pay per account thing).
So yes, reasonable or not, secure or not, there is a business supplying "secure" communications for businesses.
