This really sounds as if it’s something obvious, something one really can not miss. But it’s not, it took me a good five minutes or so to find how to filter the mail in Gmail by labels.
Labels, for those of you who do not know, is like putting mail into different folders or categories without moving them into other folders (i.e. keeping them in the Inbox). If you download mail from an external mail account, for example, you can choose to have it labeled automatically. It will then receive the label corresponding to the email address of the mail account you are downloading from.
One can also, of course, create own labels and apply them to different mail. This can be achieved by going into Settings and choosing Labels and pressing Create. But the main question here is how to filter by labels and how to search them! Labels are useless if you can’t actually filter the mail to exclusively show them!
The key lies, as so many other times, in the Gmail searchbar. This Google-powered wonderful little input-bar of rejoice let’s you do numerous things inside Gmail relating to filtering and searching. As with the regular Google searchbar you can apply certain rules to the search by adding parameters infront of the query such as define: and related: .
Solution
To search for (and essentially filter out) certain labels you only need to add label: in the searchbar and type parts of the, or the whole, name of the label you’re looking for. Gmail quickly and easily grabs all mail with the corresponding label(s) and displays it in a green box. One can also open an email with the label one’s looking for and just click the label itself. Either way labels are a very handy way of organizing mail.