You need to set up each device on which you manage read and send e-mail as IMAP if you want to sync mail across devices.
Superuser since 2015/16 Use Kudos to say thanks Mark answer as "helpful" only when the problem is solved Please don't send me private messages unless I ask you to. I do not work for VM. The advice I give is based on my best understanding of VM policy and practice. You rely on it at your own risk.
PS. You really should have created a new thread rather than append to an old thread marked as solved.
_________________________________________________________ Graham I am a VM customer. There are no guarantees that my advice will work. To say thanks click the kudos thumb. If I have solved your problem please click the helpful answer button.