That sounds like both of the email programs are set to automatically delete the email from our server when they are downloaded. So once one of them gets the email it deletes it so the next device that tries to connect and get it will find nothing.
Try setting the delete from server to Never and see if that changes anything for you. Hopefully that will be all it takes. Or look for a setting that says something to the effect of "Leave a copy on server" and make sure that is set.
Is this the only device you access your emails with? If it is set up to sync, and the emails are being access and possibly deleted or moved on another device, this would cause them to disappear. If you are unsure, try changing your Email Password and see if this continues to occur.
My Apple mail is synched (or supposed to be) for my MacPro and the iPad Mini. I was not moving or deleting anything. When a test mail I sent arrived on the iPad, did not move it to Trash, and I closed Mail to check the settings, and then reopened Mail, the message was gone, gone. Nothing in the Trash box, etc. My settings are such that mail is to be deleted only after a week. I then found that the last 2 test mails I sent alternated between arriving at only one device—iPad or the Mac.
By the way, I just changed my password yesterday.
Thank you. This suggestion worked.
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