Using IMAP on iPhones is notoriously difficult because each version of iOS has a different way of handling a standard IMAP mailbox. The differences are subtle but enough to cause end users issues. In this article I hope to try and put some of that right.
- when deleting an email the user gets an error message that it could not be moved to trash
- not emptying trash
- when trash is emptied on iphone trash, the emails are not marked for deleteion (i.e. purge) and are not actually deleted.
- the iphone might be utilising a local trash store and not the one on the server
Notes
- Different versions of office and iphone IOS might have different default ways of handling imap email deletion, ie some purge but do not delete. Outlook 2010 when mail is deleted sends it to trash, when deleted from trash actaully deletes it in the IMAP mailbox.
- iPhones have the option to delete/prune emails from the Deleted messages folder after a set period, it was mentioned somewhere that this could be set to never.
http://www.fixedbyvonnie.com/2015/02/cant-delete-emails-ios-8-iphone/ - The purge thing is a stupid thing, an item can be marked for deleteion and as such gets a strike through appearances (not all platforms), these files by definition in the IMAP protocol are not deleted until the deleted emails are purged. However different OS and software handles this differently and can appear not to use the purge feature because they delete the email and then purge it immediately, or that there is a setting to hide emails flagged for deleteion.
- purging does not usually happen until you navigate to another folder (unless the software is set different or possibly when a sync is done)
Sent to a client
The issues you have been having are related to how different version of outlook and aplle iOS handle IMAP protocol (your email), every setup is slightly different.
Here are some links to help with your iPhones not deleting emails and general information:
- How to fix iPhone IMAP error “unable to move message to trash”
- Fix - The Message Could Not be Moved to the Mailbox Trash iPhone
- Why do my deleted messages have a ‘strikethrough’ in IMAP on Outlook?
- Purge IMAP items marked for deletion (Outlook 2007)
- How to Empty the IMAP trash folder
- How to Delete All Email from Mail Inbox on iPhone & iPad
- Why can’t I delete emails from my iOS 8 iPhone? This is quite a good article