Solved How does outlook know which emails have been downloaded

Microsoft Outlook 2010 software
May 17, 2017 at 01:33:57
Specs: Windows 10
Hi, I had a situation which a handful of emails were downloaded again, and I can't see why. The UIDL thing sounds feasible, but if it was this then I would expect ALL emails to come through again.

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May 17, 2017 at 04:05:48
Check your account settings for the incoming (POP3) server, it may be set to "leave a copy on the server".

If it is, you need to untick that option, then click 'OK'.

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May 17, 2017 at 06:35:24
✔ Best Answer
But if one unchecks that option... it means once it (a n email) leaves the Server to any client app - it's gone for good.

Many of using pop3 prefer to have messages left on the server (which pop3 allows) and not use imap which mirrors a change to all clients immediately.

This may be a glitch on the email provider itself - they may have been playing with their servers? Which email service are you using; yahoo, ( as was) gmail, or what?

If you're using a yahoo account then that is increasingly an issue with yahoo based emails; they get dumped down again a any time... And it's no use contacting yahoo as they will simply direct you to their faqs section; and then suggest you use their freephone number for personal support. Don't use that freephone support - it free to call but after that it costs for anything they may offer to do. The phone support is in India and they will offer to remote into "fix" the problem... Invariably they simply scan your system using apps etc. which are free to download and use yourself...

M$ will suggest you rebuild the Office/Outlook client account to resolve the problem if it persists...

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May 17, 2017 at 09:47:06
Thanks trvlr, you are hitting the nail on the head. It isn't that I am leaving the emails on the server, because that is exactly the behavior I want and also if it was to do with me ticking the "leave email on server" all my emails would be coming through again. I am using a local provider in NZ. Funnily enough, they used to use yahoo as their email provider and have resorted to using a local company, which we migrated a couple of months ago. But your answer about yahoo is exactly what they are doing as well. They are telling me that it is my settings and offering to remote on to my machine. I believe that they were probably playing with things their end and disrupted the files, as it is only a handful from various days, and it is not continuing to happen, but has happened once before. If it were my settings it would be happening all the time. I thank you for this answer, as even though it doesn't totally fix my problem, it is pretty much verifying what I believe too.

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May 17, 2017 at 19:36:20
Just for general info:

Leaving emails on the server means you can still download them onto other devices. Even if this is set, on any particular device they will only come down once.

If you don't keep them on the server they will download once on whichever device you use but will not then be available to come down on others.

A typical way to set things up is to only set your secondary devices to keep them at server so they all will always come down on your main device.

Apologies if you know all this.

Always pop back and let us know the outcome - thanks

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May 18, 2017 at 00:35:43
That applies to pop3... If however one uses imap then should a given email be deleted be, it from the server or any other device/client, that deletion is mirrored to all devices (server included). Thus the email is lost to all... That issue with imap is why many of still prefer to use pop3... Sadly M$ and many others now are forcing the decline of pop3 in favour of imap. So much for freedom of choice...

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May 18, 2017 at 02:54:22
I didn't think using imap deleted it off the server. Imap only deletes off other imap devices, so that all imap devices are synced ? I have two apple devices setup as imap. I like to ba able to delete emails from these, but not effecting the email server nor my outlook, which is setup with pop3 and setup to leave emails on the server. I use my outlook this way as a means of being able to backup my emails. The mentioned emails were downloaded twice on my outlook, then I,found they were also downloaded twice on my apple devices, which is why I suspect that somehow the UIDL was changed on the email server. But they are denying this and saying it is something on my settings. I have checked all my settings and as far as the can see, they are all fine. Thanks for everyone's inputs, it is making me understand the goings on of how emails function and is very educational

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May 18, 2017 at 05:02:04
My own experience - and I have tested this too - is that if one deletes an email from any location then that deletion is mirrored on all locations...

I deliberately sent myself a "test" message/email. Hotmail/ is now imap (M$ have forced this on users) Created an client account using imap on my iPad and iPhones and in due course deleted the message from one of them. It disappeared from the other and also the sever pretty quickly too...

What alerted me to the this issue was when suddenly hotmail (and went from pop3 to imap and we were given little if any warning about the changes. I lost a whole slew of emails in that transitions. True M$ did restore them (but insist that now they no-longer use pop3 on their email. servers. Their fudge - which I have yet to fully fathom - appears to allow a degree of pop3 but one has to be careful when setting up any client system to ensure you don't end up with that account being imap.

Like you I like leave emails on the server as form of cloud storage; and it has been useful at times. I know one can transfer emails to a separate folder within the on-line account profile; but that is such a PIA... The olde hotmail worked fine - it wasn't broke - yet the phyxed it... (and typically M$ made things a lot less user friendly (and I suggest no more secure than before).

My Macbook and Mac Mini, and iDevices are still pop3, and for the present emails remain on whichever client unless I personally choose to delete it from there. I have noted yahoo is now imap...; and discovered that much the same way as I did re' hotmail/

Office/Outlook default is to removing from server once an incoming email has been downloaded. That can of course be changed via the Advanced setting to leave on Server..

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