Unable to send emails since today

I’ve been using v8.0.3385 (83a873c) since 21-Aug-20 without a problem but since today have been unable to send emails. Webmail works fine.
No account settings have been changed within eM Client. Using the fix button in the account disagnotics results in a red error.

I enabled logging and can see the following in the log:
MailClient.Accounts.ConnectionException: Invalid server reply when connecting: ‘Unexpected end of stream.’.
at MailClient.Protocols.Smtp.SmtpSendCommand.Connect(WorkerStatus status)
at MailClient.Protocols.Smtp.SmtpSendCommand.Execute(WorkerStatus status)
at MailClient.Commands.Command.Process(WorkerStatus status)

An Android phone and iPad can send & receive messages.
Does anyone have any ideas?

Does anyone have any ideas/suggestions?

Try deleting the account and then re-create.