V3G
I think you should consider the 3G market. It is already a fact that 3G sucks when it comes to internet gaming and even VoIP.
The people that use it are people on the move. Email, lawyers sending documents, developers on site and similar. Sure, I agree that it will become expensive if some idiot sends you 1GB of spam, EXEs or your PC sends it via malware etc... but you some responsibility will still be on the user's side. In that case use something like MailWasher to strip spam.
I am still using Hetzner as my mail and HTTP server. With it I can block spam and view incoming emails. So far I have been in control. If I suddenly see a 2+MB email coming in I go into my account and view the current download and decide if I want to continue downloading. If it is from a unwanted source I kill the download, delete the email and add the person to my hate list.
But restricting sending emails with common attachments is a problem. I would suggest that all ZIP files are left alone. If you zipped the EXE (which was a conscious deed from the user's side) the file is (1) smaller and (2) not executable immediately when it arrives at the other side. What I don't like is the smart software that scans the type of files in the zip file. Leave that alone. I renamed the files to obscure names and the SMTP server still figured out what it was. It is my stuff, leave it alone.
So the risk is that some malware program sends out 1GB of EXEs. But at the same time I might be sending 1000 clients each a 8MB update on their access control software, and with overheads it turns into 1GB of emails.
So blocking all undesirable attachments is not going to work. Maybe to protect the 3G client send warning SMSs at 500, 800, 900 and 1GB levels and then CUT THE SERVICE OFF at 1GB. You must then go into
www.vodacom.co.za and activate out of bundle service with your cellphone no and password. Maybe we should be able to set the limit when service is cut off. So if your 3G is permanently on and some malware decides to send stuff like crazy it will reach a safe limit. Next morning you find your service has been halted, you kill and delete the malware program, reactivate the service and continue.
Maybe the user must have the ability to set legal email attachments. I always have some kind of monitor open and will see in a very short time that something is going on. Somebody else might leave their connection unattended at night.
So it boils down to flexibility. I agree that there must be some form of control, but maybe that control must be in the hands of the client and not Vodacom.
VMS