Failed mail shipments are marked with a red cross.

It would be useful if this could also be seen at a glance by selecting these options at the top: sent, delivered, read... now you can only see who read them by clicking on each customer individually, then by clicking on 'notifications' in the profile - for a campaign to a large group, this is quite time-consuming, and it is not always correct (did a test where it was not visible that I had received and read the mail) - so if you select READ, it would be useful to see those who have read the campaign will appear unselected at the bottom.

It would be an added value in sending targeted campaigns from Optios :-)