Cannot send Message for Outbox

1

I have installed and activated eM Client and have two messages in my outbox. When I try to send I have an error message - cannot send message from field address “…” not accepted for reason 5.1.0 Authenitification required OFR 304_402(402)

What am I not doing correctly?

2

Hi,
please check “Server requires authentication” in your account settings.