Sometimes we hate google but sometimes we really appreciate the services it provides.
Gmail is definetelly a blessing for anyone who has used email. In particular it has 3 features that are saving me lots of time everyday - archive, labels and filters.
I am probably receiving 10-20 emails everyday which can amount to more than 300 emails at the end of the month. 300 emails in my inbox is what I consider a big mess. I could just mark anything not useful at the moment and hit the "archive" button but, I would just be cluttering my "archives" and it would only be obvious only later when looking in them for an old email.
What I usually do is mark all the posts that are related and then from the "more actions" drop down I pick the appropriate label or create a "new label" and then archive them (alternativelly you can create labels in "settings > labels"). This way when you go back to your archives you can get all related posts with the press of a button.
When my inbox has come to the point where picking the related posts is a mission just by itself, then its time to call filters to the rescue. Lets say you have a bunch of emails (from different people) related to a project.
- filters > create new filter
- insert into "from" field
email@example.com | firstname.lastname@example.org
- press next (if you have inserted the parameters correctly gmail would have found all the related emails at this point)
- mark "apply the label" and "choose the label" from the dropdown
- make sure you mark "also apply filter to x conversations below"
- create filter
Now you can just click on your label and from "more actions" choose "archive" to archive all this related emails.