Intermittent Username/Password Pop-Up in Outlook and other Email Clients - BTInternet/Yahoo

I have a number of clients who are (sometimes) unable to send and receive due to Unrecognised Username or Password  and an associated PopUp although the credentials (and other settings) are absolutely correct and frequently work. It is always possible to access mail online using the same credentials at the Yahoo site.

I have lost count of the hours I've spent re-explaining and demonstrating the problem to different BTInternet support people over the last year but am glad to say that my latest client's issue has just been escalated to Yahoo Level 3 Support!!

I have been told various things over this last year including:

There was a major issue with Yahoo which lasted at least 6 weeks late in 2011 which prevented many users of many email clients being unable to access mail due to the PopUp.
If a second device (a phone for example) is configured to access the same Yahoo mailbox this can cause other clients (Outlook or Windows Mail for example) to be unrecognised due to some kind of contention.
There is no point in using a local mail client these days - just use webmail

Has anyone had any experience of this major annoyance which only seems to affect BT Internet not BT Connect. Obviously if anyone knows a fix my clients would be overjoyed!
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jasonJladasConnect With a Mentor Author Commented:
It seems the problem may finally be resolved!

It had been suggested earlier that the problem was some kind of contention with a second device accessing the same mailbox and we felt this had been eliminated by turning the client's Iphone off during our Outlook/Windows Mail testing.

It was later suggested that turning it off wasn't good enough and in fact you need to go into IPhone settings and turn off one or both of "Push"  or "Automatic Fetch". When this was done  both Outlook and Windows Mail began working without pop-ups for the first time in 48 hours.

I had been told that using both of these client applications (at the same time) would cause the problem to re-occur, so, being a sucker for punishment, I tried it and it did! Unfortunately having done this they no longer worked individually.

I then discovered that by signing out of Yahoo Web Mail and logging back in it was possible to "reset" the contention problem so that the clients could be used (individually) again.

So to Recap:

If an Iphone is in use Push (and probably Fetch) should be turned off.

2 clients should not be used at the same time>

If the contention issue arises it can be reset by signing out and back in to Yahoo Web Mail.

If web mail is set to "keep user logged in" simply accessing Web Mail is not enough.

Hope this helps anyone else with same problem.
Stelian StanNetwork AdministratorCommented:
Have a look on this question with the same topic.
Hi, a random thought and my suggestions.

Assuming these clients are all at one site behind a firewall. If you have the firewall features enabled, there is a feature called TCP Syn Checking which can cause delays and breaks in connectivity. This can be a plausible reason why your users are randomly getting login prompts or potentially some websites not loading correctly.

I'm also assuming that these clients are on fully updated and service packed machines, this goes for OS and Outlook.

What antivirus application is being used on these machines? Have you tried to disable to mail scanning part of the AV to eliminate a subset of users and reviewing.

If BT is hosting emails for a custom doman name, move them to Google Apps for Business, problem solved.
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jasonJladasAuthor Commented:
Sorry clonyxlro, your link seems to relate to a different scenario. Its not specific to Outlook, I know it affects Windows (Live) Mail, and (according to BT) Thunderbird and OE also.

Nettlo, thanks for thoughts. No, not all one site. Various domestic users with various AV. Mostly up to date and all using BT internet/Yahoo. Yes have tried disabling AV and Firewall to no avail.

By the way I received a totally unintelligible voice mail from Yahoo Level 3 Support which I later discovered was telling me that they had found an issue with the server that had been resolved by re-synchronising the account and that the case had been closed. Unfortunately the problem was absolutely unchanged and it took another 40 minutes of watching yet  another Level 2 Support person going through the same diagnostic script before the case was re-escalated to  Level 3. I live in hope!
Stelian StanNetwork AdministratorCommented:
Sorry about that. Hope that eventually the problem will be solved.
jasonJladasAuthor Commented:
Its not really my solution, just a hard won result with contributions from about 20 BT support people.

It seems my problem last year had the same symptoms but a different underlying cause.
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