In the webmail app, if you change the email selection, it automatically checks the "Select" box. This is bad UI programming, because it leaves items in a state of "Checked" that the user hasn't actually marked as selected. Where this really becomes a problem, is after you have marked a selection of emails as Spam, because it instantly "Selects" the first one in the list after the action is complete. So when you click on additional emails, the first one is still part of the selection, meaning it gets caught in the next "Mark as Spam" collection, or next *Bulk* action of any kind... including "Delete". I had two emails disappear and it was only when I watched the selection process at work, that I realised what had happened and when I checked, the emails were in the spam folder.
CheckOnClick is not default UI behaviour in Windows, because those two elements are deliberately separated in the UI component functionality. If you are making a Winforms app with checked listboxes, you have to deliberately choose to have "CheckOnClick" as the behaviour.
The checkbox needs separating into it's own component and that should only activate, when you specifically click it. Changing the selection with cursor keys should not mark that box as checked. Clicking to view the email should not mark that box as checked. Neither should that item be selected as the result of a multi-selection function in the app. i.e. as fall-back behaviour when the list is rebuilt. When I personally write apps with this functionality, I always make it an option and that's ideally what it should be here.
This is probably the result of a mobile developer with limited (or none at all) understanding of desktop functionality standardised processes. Click the email item to view, click the Check-Box to select, that's desktop functionality with this type of list item. Sadly, app development is falling into the grip of mobile developers and as such, mobile functionality, which is wrong. The mouse is a precision selection tool, desktop apps don't need "Fat-Finger" compensation building into them.
There is also another issue with the "Mark as Spam", which frequently results in this error:
The connection to remote server oxsmtpwebmail.talktalk.net timed out while awaiting the response. Please try again later.
And the spam emails get dumped back into your inbox after several seconds. I suspect it's probably down to the sheer number of reports that get submitted, because of how much Spam comes through this portal. Bitcoin seems to be the latest Spam trend, I get a pair of emails every day about it.
The auto-selection of the next email in the folder list after an action on other emails is, I agree, an undesirable default. It has been drawn to the attention of the email project team. We're awaiting to see if this default action is changeable.
The try again later message could be because the reporting of the spam couldn't get through.
When you tried again did it succeed?
I've raised this with the manufacturer and it seems they'll look at the options on this although it's their standard setting. It's been suggested that meantime you might try changing the page view as it makes it a little clearer in other views. I've had a look at that and I can see that it's a bit easier to manage if you use compact or vertical view as they both put you fully in preview of that next mail. When using those settings I think it makes more sense to have auto select of the next mail. In the other views I agree with those of you who dislike this option and think it's easy to delete in error.