Duplicate email after AT&T/Yahoo mail merge

I was able to correct the issue of duplicate sent emails by turning off conversations in the actual yahoo.com email settings.  This page explains how to get there.

https://help.yahoo.com/kb/att/new-mail-for-desktop/SLN28824.html?impressions=true&guccounter=1

I tried that a couple of weeks ago and checked again just now. Unfortunately turning off conversations didn't work for me. I still get two copies of every email I send, one read and one unread.

okay - been messing with this for days and seemed to have corrected my version of the problem.

My duplicate "sends" appear only in Outlook for Mac (Office 365 suite via my local community college).

The "sent" duplicate messages (one with blue dot and the other without) DO NOT appear in Yahoo Mail server account on the web. Nor do the duplicates appear on my iPhone Mail IMAP client app nor on my IMac IMAP client app. The only place the duplicates appear are in the Outlook for Mac program "Sent" and they only do so if the message was sent from that program (i.e., messages sent from my iPhone Mail IMAP client app do not create duplicates in Outlook.

Now to the solution (at least for me)!

Though on the first time I tried this it didn't seem to work, today I once again went into 

Outlook> Preferences>Accounts>....pacbell.net>Advanced>Folders>Sent (Send [Server])> and checked "Don't store a copy."

Voila!!! Did a test send from my Outlook pac bell.net account to my gmail.com account then waited a few minutes and checked the Outlook "Sent" folder. There was only the one sent test message (with a blue dot) and no duplicate. And, the same one test message (with the blue dot) also appeared in the Sent folder on my iPhone Mail IMAP client app.

So, let's hope it wasn't a hiccup of "do the right thing" (but just for now to lull hime into a sense of false security).

Hopefully, others with the same circumstances as me will post if this solution works for them too. 

I trust this makes sense and that t may work for those of you with the same

Below are the rules for the handling of a sent email message when sending through a Yahoo SMTP server (both POP and IMAP)**.  These rules only affect the handling of the sent message on the sender's side.  They have no effect on the actual sending of the message.  Only a single copy is ever actually sent.

1. When sending the yahoo SMTP server automatically places a copy of the sent email in the server Sent mailbox (which is always mirrored in the webmail mailbox).
2. The server copy is always flagged as "unread" (hence blue dot in the webmail).
3. If the email client app (e.g., Thunderbird, Outlook, mobile email client apps, etc.) settings have a "save copy of sent email in mailbox X" (or similar wording) the client will save a copy in mailbox X even if X is specified as the Sent mailbox.

So when you send from the client yahoo IMAP SMTP saves it's copy of what you sent (rule 1 & 2) and the client saves it's own independent copy (rule 3).  It's up to you to decide whether you want your client to do that additional save.  Your choices are (a) leave it do what it's doing (after all how often do you really need to look at the Sent mailbox anyhow?), (b) set your client to save sent email into another mailbox other than Sent (then you only have one copy in Sent and the other in your extra mailbox), or (c) set your email client to not save a copy at all knowing that rule 1 will save a copy for you on the server and because it's IMAP you will also see it in the client's Sent mailbox (possibly after some delay depending on the sync rate between client and server).

By definition all IMAP configured clients are kept in sync through the server.  So if you don't follow the same conventions for Sent on all your IMAP clients you won't see consistent behavior (some explicitly saving sent email to Sent and some not).  If one allows the additional save to Sent, and that one is also doing the sending, then you will see the two copies on all your IMAP clients (again after a little delay).

Note I listed those rules as for both IMAP and POP.  POP too will save a ("unread") copy of the sent email (rules 1 and 2) but the client's "save copy of sent email in mailbox X" of course won't affect the server since the server cannot see changes to a POP client's inbox (except for possibly deletes but that dependent on separate POP setting).  So for POP you probably do want to set the client setting to save a copy in the client's Sent mailbox.

This must be a recent change to yahoo SMTP handling and I have no idea why it was changed.  With the exception of flagging the sent copies in the webmail Sent as "unread" (that seems stupid) I am not sure this is a incorrect implementation according to the standards.  The original yahoo SMTP conventions didn't include rules 1 and 2 so that it was up to the client to do the save to the client's Sent mailbox which again by definition of IMAP would appear in the server/webmail Sent mailbox.  Also I seem to recall that stuff sent from a POP client never used to show on the server/webmail Sent mailbox either.

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** Determined from experiments with Thunderbird.

Thank you for the explanation.  Unfortunately, now when I send email from my sbcglobal account other than through Outlook 365 on my laptop or the Yahoo Mail app on my phone, the recipients get two - and sometimes even three - copies of each message.  I am really frustrated with this, especially because the Yahoo Mail app also has bugs (for example, sometimes doesn't offer a Reply All option).

Is there a customer service or tech support phone line or chat option for Yahoo Mail?

@Tottencourt 

"Unfortunately, now when I send email from my sbcglobal account other than through Outlook 365 on my laptop or the Yahoo Mail app on my phone, the recipients get two - and sometimes even three - copies of each message." (experimenting with a new quoting convention since we cannot selective quote anymore)

So if your laptop client app and phone client app are working correctly what else are you using to get multiple instances of a single message sent?  Certainly the webmail isn't do it.  Whatever it is you are using I believe is the source of your problem, not the yahoo servers. 

"Is there a customer service or tech support phone line or chat option for Yahoo Mail?"

Not if you are using a att email account.  Yahoo will just ask you to contact att.  And att tech support knows nothing about email unless it's written on their canned reply scripts.  Maybe you should contact the author(s) of the other app you are using.

It happens using any other app on my phone - Samsung native email app (which I have used for years), Gmail app, Outlook mobile app.  It doesn't happen if I use those apps to send email from other email accounts (e.g., gmail or Microsoft Live).  It is clearly a new issue with the Yahoo servers and how they interact with mobile apps other than Yahoo Mail.  Others have reported the same problems with different apps and different phones, including iPhones.  I just wish I could get someone from Yahoo Mail to address the problem.

@Tottencourt 

Google search for "yahoo help".  I know they exist.  You just have to find them.  Good luck.

I didn't suggest it in my post 16 but there is a fourth choice to all of this yahoo mail nonsense.  Dump them and find a real email service provider that actually knows how to run an email service!  This is usually the last thing I post in topics with those frustrated with yahoo email.

Update: I found a live person at Yahoo who told me that Yahoo is only "partners" with AT&T and does not have responsibility for or offer support for sbcglobal.net email accounts.  I called AT&T and after being passed between two UVerse techs, I was transferred to a special line for email support, only to get a message that the hours of service are from 7 AM to 1 PM EST before being disconnected. 

Luckily, I got the direct number to the AT&T email support line before being disconnected.  The number is 877-285-0144.  I will call in the morning and am hoping if enough other people who are having the same problem call in they might do something about it,