You have just prompted me to check our email validation, all fine, thanks! Interesting aside, I run an online store, something like 90% of customers have an em

You have just prompted me to check our email validation, all fine, thanks! Interesting aside, I run an online store, something like 90% of customers have an email address from one of a main providers - MS, Google, Yahoo, Apple, and as we are in the UK BT. We have also seen a significant correlation between customers with a @btinternet.com or @yahoo.com and those that contact support more. You could say they are significantly more likely to be "difficult" customers. Of course my parents have a @btinternet.com email address... Finally, Yahoo has by far the worst deliverability, all our email (transactional & support, not mailing list) get through to other providers but with Yahoo it's as much as 50% of email just disappears at times, it's not even in customers spam folders.