Transactions involving small amounts of bitcoin are not allowed because they are considered spam that wastes resources on the blockchain. The smallest amount you can spend is 5430 satoshis.
This. Basically you're trying to send 323 satoshis. The minimum you can send in most cases is 5,430 satoshis. However, there are ways to attempt to send amounts lower than this (emphasis on the word "attempt") although it's not recommended. You will need to download a client configured to allow non-standard transactions. And even then, since transactions involving amounts lower than the 5,430 satoshi limit are classified as non-standard, they are unlikely to be relayed by nodes which means that your transaction probably won't go through.
Electrum also enforces a minimum transaction fee of 10,000 satoshis (or 1,000 satoshis if you change a few settings). This can be avoided but only in cases where the transaction fulfills certain criteria such as age and transaction size which would most likely not be true in your case.
