Heading states there is a problem with my email address

The opening page when I check in has an orange banner stating there is a problem with my email address.
As far as I can see, it is correct as displayed.
How do I find out what that really means?
Thanks for any info. This is quite puzzling.

It seems that your email provider was mistaking our messages to you as spam and then blocking them from being delivered. I was able to correct this issue on our end, but if it occurs again in the future you may need to contact your email provider directly. Sorry for this inconvenience.

Many thanks for that reply. I wondered where the monthly issues had gone. We will have a look in the spam file, and also I’ll see if there is some kind of filter set up which I shall remove.
My apologies to you also.