I have a client who says that he used to have the following setup and behavior. He has company email thru some small-fry hosting company (IMAP). He has Outlook on Win7 and he has an iPhone with the included Email App. Both access his company email account.

He says he used to have and would like to have again the following behavior: Both the iPhone Mail and the Outlook see all emails. But they are out of sync in every other way. If he deletes an email from Outlook it's still there on his iPhone Email and vice versa. If he reads an email in Outlook it's still marked unread on his iPhone Email and vice versa. (I repeat, this is the behavior he used to have and wants again.)

He says nothing changed in his iPhone settings, but Outlook got reinstalled and now the two are in sync. And he doesn't want them in sync. Does anyone know how to set up Outlook to be out of sync with iPhone Email using the above behavior?

I thought about having a separate local Outlook folder that all his emails get auto-copied to where the IMAP server doesn't synch them up. But he said he had nothing kludgy like that and he doubts anyone set up any of those Outlook rules to accomplish this.

  • What if you set up Outlook as IMAP and his mobile email as POP3 or something to that effect? Outlook would be synced but the mobile emails would be static local copies so changes in Outlook wouldn't affect the local copies on the phone (or vice versa).... Although I still can't fathom why you would WANT that. – Ciaran McKenzie Jan 26 '18 at 15:57
  • If it was Outlook that got reinstalled then I would suspect that's where the change happened, so leave the phone set up as is, and if the Outlook is now IMAP, change to POP3? – Ciaran McKenzie Jan 26 '18 at 15:59
  • OK, I thought POP3 meant that email could only be seen by one client in the first place. So I was contemplating the idea of POP3, but I figured that was throwing darts in the dark. But OK, thx for the advice. – Joe C Jan 27 '18 at 4:04

You need to use POP3 instead of IMAP on all mail clients

The reason the two devices are in sync is because of how the IMAP protocol works. When mail clients access the mail server via IMAP, changes are bi-directionally synchronized between the client and server. For example, if a message is deleted on the client, that change is propagated to the server and the message is removed there as well.

POP3 on the other hand is (mostly) uni-directional. If a message is deleted on the client, the next time it talks to the server it doesn't tell the server to remove the message. As a result, when another mail client (e.g. your user's iPhone) connects to the server, the message will still be there.

For this to work as described in this answer and how you described it in your question, all mail clients must connect to the server via POP3. Otherwise any IMAP client has the ability to remove messages from the server before a POP3 client would be able to download the message. The discrepancy this creates with your client's assertion their iPhone's email configuration has not changed can be explained several ways:

  • The iPhone is already using POP3 (doubtful based on how the behavior you describe) and that's how Outlook had been configured as well
  • Outlook was using POP3 and left running often enough such that it was able to download new mail before the client deleted it from their iPhone
  • Your client infrequently deleted email from their iPhone, and when he did, he didn't notice Outlook didn't (couldn't) download it the next time it was opened.
  • Thx a lot for your thoughtful and detailed answer. I thought about configuring Outlook as POP3, but my understanding had been that if you configure a client as POP3 it would take an email delivery so that that email was no longer available for any other client to access. So I thought using POP3 technology was a non-starter. But according to you I was wrong. My client told me he never turned his Win7 / Outlook PC off, so it likely always took the e-mail before he read and deleted them via the iPhone could delete them. So I'll try your Outlook in POP3 idea. – Joe C Jan 27 '18 at 4:01
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    Outlook w/POP3 can be configured to delete the messages from the server after retrieving them. Be sure to disable this entirely. – Twisty Impersonator Jan 27 '18 at 4:25
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    You were spot on. It was your middle theory about Outlook being left running often enough to download emails before the iPhone deleted them. And now I had another client with POP3 and this time the "Delete my mail after retrieving them was set" so now I've seen both. :) – Joe C Feb 9 '18 at 18:32

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