I recently finished implementing a new feature for PopTrayU, conditionally disabling automatic checking for an email account based on the time of day. This feature already existed on a global level: you could disable checking for all accounts, so that your computer would not check for email while you’re sleeping or awaken you with a loud “you have new email” notification sound. But some users, particularly users who work from home and use the same computer for both work and pleasure, were making a feature request that they’d like to be able to turn off notifications for their work email outside of normal working hours.
The part of the implementation that was most difficult, of course, was the requirements analysis and the detailed design. On the surface, this feature seemed pretty straight-forward, but as I started to dive into actually implementing it, a lot of nuances come up where it isn’t exactly clear how this feature should work, and the design has to be hashed out in more detail, and the requirements clarified.
Each account has a status icon indicating whether the account is disabled or has new email or no new email. (For the sake of clarify, lets call this new per-account no-auto-check feature “sleeping”.) Should the visual appearance of an account that is “sleeping” appear like a normal account or a disabled account? Something else? What should the status-bar for the account say when an auto-check happens, but a single account is skipped because of the time? If the user presses “Check All Accounts” manually, should that skip or include accounts that are sleeping? What if they press “Check” for a single “sleeping” account?
Once I nailed down the design, implementation was pretty simple. Because the feature existed on a global level, most of the implementation was quite similar to the logic and UI of how it was done for the global level.
As far as how I decided to resolve some of those issues:
An account that is disabled is represented by an envelope with a red minus symbol on it, like this: 
Previously, this was the only reason a specific account would be skipped when an auto-check occurred. Now we have two reasons an account might be skipped. It could, for some users, be handy to be able to differentiate the reason the account is not automatically checking, especially should they be troubleshooting settings gone awry. I experimented with making a new symbol that resembled sleeping, like something with zzz’s or a moon, but given the limited amount of space in a 16×16 image, trying to make an image that is clear and recognizable is difficult, so I decided to use the same symbol as a disabled account, but use a contrastingly different color to differentiate the different status. 
As far as when to check/not-check:
- Automatic timer-interval checking, pretty straightforward, sleeping accounts should be skipped.
- Manually pressing the “check all” button: more ambiguous, it’s not really an “auto-check”, but it behaves a lot like one. In the end I decided “check all” should replicate the behavior of auto-check, but on-demand, so accounts that are not in a state allowing automatic checking should be excluded, so it should behave like a disabled account.
- Manually pressing the “Check” (this account) button: this one seemed pretty straightforward, even a disabled account will check when pressing this button, so a sleeping account should definitely check in this case.