Showing New, Old and "Not Yet Emailed" in a table column through symbols/colours

Question

We have table data displayed to clients where each record can be in one of three states:

• Not yet emailed
• Emailed in the last two weeks
• Previously emailed

It's a dashboard system that gathers enquiries on services, and once every two weeks the company is sent an email showing their leads from the last two weeks. We need a way of showing someone on the dashboard which state each enquiry falls in to.

Space is limited, so ideally we'd like a single icon/symbol (font awesome, glyphicon, etc.) that can be coloured to signify what each state is. (Hover-overs will be used for explanations, however without touchscreen support we'd like the icon to be as self-explanatory as possible.)

We were thinking an envelope - either green, yellow or red - but I was worried that this could indicate that red envelopes were not emailed, as opposed to previously emailed.

A second idea was using two symbols - an envelope beside either a star, a tick or a "history" clock, but these seem too ambiguous.

Another completely different idea would be highlighting rows and showing a key, but again this would take up a lot of space.

Table Data (symbol to go on the X):

|       | Enquiry Date | Name             | Job Title         | Company     | Email        |
|   X   |              |                  |                   |             |              |

Any ideas?

Answer 1

Don't rely on colour only

First, I would urge you not rely on colour for semantics, this is to consider the colour blind (8% of male population). You can have the icons coloured, but you should provide different symbols for each state.

Icons are nearly always unclear and ambiguous

Second, nearly all icons are ambiguous and unclear, particularly for new users, particularly if there are a few of them on the interface. I'm not going to attempt an icon suggestion - such a practice is largely a guess work and not based on empirical UX process. What's more, icon suggestions questions are typically out of scope for this site (see FAQ), exactly for the reasons I've just given.

Legends

What is important to remember though, is that you may use any implicit coding (such as an icon or a single letter) if there is a legend for the users to look at. Also, the more the system is based on repeated usage, the less you need to worry about the unclear symbol you provide.

The main challenge here is really provide symbols (icons) that are distinguishable enough for experienced users to remember each symbol without having to consult the legend.