Send a message to any Bitcoin address, easily visible in any block explorer.

Copy paste the outputs into your favourite wallet such as Electrum and send the transaction.

What it can look like:
Each message line is displayed via an artificial vanity Bitcoin address which no-one holds the keys to. Hence the small BTC outputs for the message are essentially burnt.
Send a message to this Bitcoin address.
Letters 0/I/O/l characters are replaced with o/i/o/L.
Character that will be used to pad each address.
Max number of characters that will be grouped into an address.
Bitcoin to send along with the message, the default (0.0000543) is the minimum amount for a Bitcoin output.
Total Amount: 0 BTC

Always manually double-check the addresses and amounts before sending.