Sent emails not being delivered from Outlook

Question

For the past week emails sent from Outlook although appearing in my Sent mailbox are not being delivered.  This is not a problem where emails are sent from my iphone.  I have made no settings changes.  This seems to be a familiar problem but research has not produced a solution as most people give up.
I am using a Windows 8 laptop with Outlook 2013.  I have set up numerous new accounts with automated settings with no success.
Please help!!

Answer 1

I too knowingly have had this problem since at least 19/1/2015.
I have Windows 7 with Outlook 2013 and two BT accounts plus Sky and Google accounts (for fallback). All have functioned well for the past three years.
No changes to my PC have been made for at least 6 months (apart from MS updates).
My wife's laptop runs Windows 7 with Outlook 2010 and has found the same issue. At a Womens Instutute meeting last night in the village it became apparent (without my wife initiating the issue) that a number of other BT eMail account customers have the same problem too.
I spent about an hour yesterday trying various combinations of operation to confirm the issues. I have found:
1 - eMails sent from either BT account self addressed will bounce back the eMails (presumably from the BT Server)
2 - eMails sent from either BT account to BT accounts will not forward (send/deliver)
3 - eMails sent from either BT account to non BT addresses will not forward (but will bounce back if the self address is included in the addresses showing that at least the eMail is reaching the BT mail server).
4 - eMails sent from Outlook through Sky and Google systems are being received by the BT system and recieved into the Outlook BT accounts.
5 - All eMails sent in Outlook appear in the Sent box
6 - eMails sent from Webmail accounts all work normally
All these tests can be replicated on my wife's laptop with other BT and non-BT addresses.
I then spent about an hour whilst a BT Technician (ABHISHEK SEN) through CHAT accessed my PC, checked all settings and declared no fault found.
Later I spent another hour on the phone to the BT Help Desk (with VIKRAM) who did much of the same, declared that there was a problem and that I would have to hire a local PC expert technician to come and sort out the problem on my PC. He would not acknowledge that there just might be a problem with the BT eMail Server system.
Finally the only common thread is that the BT accounts are sub-accounts of my main account and that I pay the bills - and of course the router and copper lines to the exchange.
HOW OR WHERE DO I/WE RAISE THIS ISSUE WITH A HIGHER AUTHORITY TO GET IT RESOLVED?
Oh! And then there is the rest of the village and gwood's machine also need to have their similar issue resolved too.
To use gwood's last paragraph: PLEASE HELP!!