Broken/Stukkend 3 : SARS eFiling's e-mail

My tax advisor just forwarded to me the reply he got when enquiring about the money that SARS (the South African tax authorities) owes me.

The following recipient(s) could not be reached:

eFilingAssist on 2009/07/23 03:16 PM
The message could not be delivered because
the recipient's mailbox is full.

That is, for a country of 50 million people, they did not think to solve this very usual problem. In fact, what they should do is not to have an e-mail address at all but only accept queries on the Web. Many organisations work like this and it is more-or-less as convenient for the sender because they could receive a copy of the sent message by e-mail, which - at the same time - confirms delivery. Is one morally obliged to even pay tax if the tax authority refuses to accept any correspondence?