Today (Dec. 31st, 2017) I am having the same issue with not receiving email from Bittrex when it doesnt recognize my IP address and directs me to an email link.  Look in my email and it's not there!  I also have Outlook.  I have had no problems till today.  I haven't been able to login all day!!  I've gone to Bittrex support and added them to my contacts and safe sender list, and have done everything they told me.  I am still not receiving emails!!!!  Super frustrated and nervous something fishy is going on!!  Have sent in a support ticket but Bittrex is super backed up!  So now what do I do.  Please Help if you have solved your issue.
Thank You