iOS18.5 Mail Creates Duplicate messages

OS18.5 Mail creates duplicate messages

To reproduce:

Using an iPhone running iOS 18.5 set up Mail with access to two different iMap accounts. I use a single iMap server for both accounts. The server runs the cyryus iMap software.

From some other device and account send a message containing a link or an attachment to one of the two accounts set up above.

Read the message that was sent, then move it to a folder on the other account. This folder can be the INBOX folder.

Attempt to access the message from the other account. This will result in the "Checking for Mail..." message.

Using a different device and iMap client access the folder where the message was moved. I use the text iMap client, pine, for this. You will see multiple copies of the message in question. They will be continually duplicated by the iPhone Mail app. If this is allowed to continue, thousands of duplicates will be created, although the iOS 18.5 Mail app will only show one copy.

To recover:

Shut down the iOS Mail client.

Delete all the duplicate messages on the iMap server using another device and iMap client. I use the same text based client as above.

Disable Mail access for the account on the iPhone.

Enable Mail access to the account on the iPhone.

Deleting and reinstalling the mail account on the iPhone also works.