Mail not getting to Yahoo email addresses

[susapra]

I operate an online store. When we update customers orders an email goes to the customer confirming the different stages. Yahoo mail account holders do not seem to be receiving these mails.

What could be causing this?

Thanks

[temi]

This means Yahoo has blacklisted your SMTP server, you should get in touch with them and request that they unblock your site.

[lucasportik]

that's very sad