What is Adobe best practice to send an output file of thousands of PDF documents to a print vendor / print facility?

What is Adobe best practice to send an output file of thousands of PDF documents to a print vendor / print facility?  The print facility may add additional bar codes, inserts and processing of files before they are printed or mailed.  We can send multiple .pdf files within .zip files, but is there another file type where we can include the multiple files to send to the print vendors, e.g, via sftp?.  Any general direction or guidance from anyone would be very helpful.