Anthony The reason this seems to work where everything else failed is apparently due that some ISP's can block the Outgoing server port 25.
By changing to another Port number (alas, check with your ISP if 587 doesn't work) it does the trick.
The following is a list of some of the applications which are reported to cause message to be marked as read.
If you use these or any other add-ins, check for a newer version - newer versions of some of these applications will not cause problems.
Updates for Windows 10 operating system are not something that you need to be terribly worried about as Windows Update automatically downloads and installs available updates in the background.Never randomly click a link as it may direct you to a malicious website or trick you to download an infected file or program.Note: Always check the address bar or the URL, to see if you are loading the correct website.These can come in a form of an email from your bank asking you to update your account information via a suspicious link or a seemingly helpful popup from a website that is offering a free registry clean up.Some malware distributors even keep themselves up to date with current events that would easily tap into an unsuspecting user’s curiosity.