email blocking from a specific sender

I am no longer able to receive email messages from a specific site.  I was receiving messages from this site up until August of this year (2024).  In my internet research it seems that this coincided with the change to block port 24 so not sure if this is what caused this issue. I am trying to log into my online account with them but in order to verify my account, they send me an email which I don't receive.  I have tried the "ask Xfinity" but all I can get is the standard questions and suggestions to search the site which none of it helps.  I can receive emails from this vendor to my @gmail.com account but nothing at my @comcast.net account.  Since my paid subscription account with this site is set up with my @comcast.net credentials I cannot access.  Is there another "chat forum", etc. that can help.  I have looked at all of my email settings at Comcast and do not have any filters set up (none are set up that would block this sender).  I am at a loss and need to be able to access my account but cannot do so until I can verify my account through an email that is sent to me.