What is the most reliable way to send a zip file via email? [closed]
I think you're actually on the right track with your encryption approach. Part of the problem is that an encrypted zip is still a zip, and may be blocked by some firewalls for that reason alone.
Have your software zip the data, then encrypt the file but not within the zip framework. You'll end up with a file that won't appear as any prohibited file type to the firewalls. A simple substitution cipher might be sufficient. Save the file without an extension.
- client-side: data -> compress -> rot128 -> dumpfile
- client sends 'dumpfile' as attachment
- your end: dumpfile -> rot128 -> decompress -> enjoy
Usually what I do is just upload my files somewhere where they can download stuff from a server. That way, it also doesn't clog up their inbox.
If you're short on space, Dropbox is a great service that gives you 2GB of publicly-available space for free (great syncing tools, too!).
UPDATE: It seems that I misread your question initially; you were in fact asking about clients giving files to you, rather than you giving them files. Regardless, my answer remains the same. If they're at all tech-savvy, then set up an SFTP server that they can upload stuff to. But still, using Dropbox is a piece of cake. Set up a shared folder for each of your clients, then they can put files in the folder and the files will be automatically synced to your computer.
I've found luck with sending either a .7z file or sending a FILE.zip.potato . I then instruct the recipient to rename the file back to .zip. It works surprisingly well.
You'd think that more email clients/server would check to see what type of file it really is, but I guess the problem isn't sending zip files, it's sending viruses in zip files. If the recipient has to rename the file to get it to work, they must know reasonably well what they are doing, so they aren't likely to accidentally rename, extract, and run a virus.
There are numerous file sending services out there that can receive an uploaded file via their web site and will send you a link to go download it. This keeps the strain of handling the file off of the e-mail servers. One such service is SendThisFile.
I think you have a social problem, not a technical one.
If I'm reading your question right, you have a number of clients who send you (zipped) files from time-to-time, a notable proportion of which can't due to their corporate firewalls. If i have that correct, I would suggest you need to make it clear to your clients that it is their corporate firewall that is being over-eager and that they need to include their firewall maintainers and -- most importantly -- policy setters in the discussion.
Most decent IT Security personnel will understand the problem and will appreciate being included in finding a solution, rather than being routed around. Which means they will help. That's assuming your clients actually have decent IT Security people, which is not, of course, a given. :-/