If the user doesn't have ecash sat, the message will only be sent through the free relay. Long press the message you sent and select raw data.

У меня есть eCash. У relay.keychat стоит крестик, при просмотре через "raw data". Я использую mint https://mint.minibits.cash/Bitcoin.

Mint "8333" works, apparently you have limited the available mints for payment.