"Mailchain client does not seem to be running"
"Your Mailchain client version is A.B.C. Please upgrade it to version X.Y.Z to ensure things work as expected."
See Upgrading Mailchain for further information on how to upgrade.
NOTE: To check the latest release version, visit Mailchain releases on Github
"Error 500: could not send message: could not send transaction: Insufficient funds. The account you tried to send transaction from does not have enough funds. Required 46528000000000 and got: 0."
The address you are sending FROM does not have enough balance to pay the gas cost to send a transaction.
Check that you are sending on the right network and that you have a balance on that account.