Currently
When an email blast is sent, a record of it is added to the "Sent e-mail" section in the administrator settings. Over time this list can grow, and some people have worried that without a way to manage it, it could eventually grow so large as to become unusable.
Workaround
While not perfect, there is a keyword search on the screen where administrators can filer the list and just see the emails that they are interested in.
Proposal
Since this list can become large, some have asked for the ability to be able to delete records of e-mails. Each entry in the Sent e-mail would have a delete button associated with them. Clicking this would delete the records of the emails.
This also means that all of the related work with them, such the ability to reuse the e-mail for future blasts and any of the tracking information associated with them would be lost.
I would maybe propose a different solution, where old sent e-mails could be archived. There would be an archive button associated with e-mail record and when clicked the e-mail would not appear on the main list, but all their information would remain. Administrators could access them by selecting a 'Show archived e-mails' on the checkbox. If the administrator wanted to restore a message from the archive they could do so on the archived message. (It might also be possible to combine the two in a way similar to how contacts can be archived or deleted).