NEW ISSUE- Zoom Webinar confirmation emails not reaching yahoo.com

Over the past 3 days we’ve had 2 webinars where yahoo.com users have NOT received their confirmation codes. Not in spam, not in trash, not in regular mail. When it was one time I assumed user error. Second time, with another yahoo.com email, I’m thinking it was a system error. Doing some sleuthing, other platforms have issues with yahoo.com and apple mail, so I’ll check that out, but wanted to know if anyone else has seen this issue and whether or not you have a work around. 

Susan