Icloud mail - not a valid Base-64 string

I can no longer send email from eMclient.

These are the SMPT settings which worked before and are correct per Apple.

Host smtp.mail.me.com
Port 587
Force SSL/TLS

Server requires authentication
use these credentials

Tried every SMTP setting - nothing works.
Tried changing ‘Signing and Encryption’ settings per another thread - no joy.

Tried different emails and the usual ‘hello world’ to myself - nothing.

I am using an apple one-time application password.

I can receive fine, I can send from my iPhone. But can’t send email from emClient.

Ran eMclient diagnostics which said there’s a problem, but the ‘fix’ option was not able to fix the problem.

Suggestions?

log file follows…

2:11:17 PM XXXXXX@icloud.com [SMTP] MailClient.Accounts.LoginException: The authentication failed due to the following reason:
"The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters.
at MailClient.Protocols.Smtp.SmtpSendCommand.Authenticate(WorkerStatus status)
at MailClient.Protocols.Smtp.SmtpSendCommand.Connect(WorkerStatus status)
at MailClient.Protocols.Smtp.SmtpSendCommand.Execute(WorkerStatus status)
at MailClient.Commands.Command.Process(WorkerStatus status)
EnqueuedStackTrace =
at MailClient.Protocols.Smtp.SmtpAccount.<>c__DisplayClass3_0.b__0()
at MailClient.Protocols.Common.AccountBase.RunIfOnline(Action actionIfOnline, Action actionIfOffline)
at MailClient.Protocols.Smtp.SmtpAccount.SendAsync(IEnumerable1 items, Action1 sentItem, Action1 completed, CancellationToken cancellationToken) at MailClient.Accounts.BindingAccountBase.SendInternal() at MailClient.Accounts.BindingAccountBase.Send() at MailClient.Accounts.AccountManager.SendAllInternal() at MailClient.Accounts.AccountManager.SendAndReceiveAll() at MailClient.Program.<>c.<AfterStartup>b__208_0() at MailClient.Accounts.AccountManager.<>c__DisplayClass82_0.<InitializeOnlineMode>b__0(Object <p0>) at System.Threading.QueueUserWorkItemCallback.<>c.<.cctor>b__6_0(QueueUserWorkItemCallback quwi) at System.Threading.ExecutionContext.RunForThreadPoolUnsafe[TState](ExecutionContext executionContext, Action1 callback, TState& state)
at System.Threading.QueueUserWorkItemCallback.Execute()
at System.Threading.ThreadPoolWorkQueue.Dispatch()
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()