Microsoft in particular has been tweaking their filters over the past few months, in a way that results with a lot of blocked emails from various different forum sites. In addition to checking the junkmail folder, check the deleted folder. In the Deleted folder, there is an option to recover (some of the) ones that you don't see there. Under Settings you can navigate your way to "Sweep", "Rules", "Junk email" and "Forwarding". Any one or more of them can be responsible for deleting/moving and sorting your emails. Have to check them all. For old email addresses such as mine, (had since early 2000s,) what they've done these past few months has been a cluster. I'm considering wiping it all out and start over. But with well over 300 rules for sorting and deleting, that's no small task.