Copy and paste your e-mail contents into a text file for safe keeping on your computer.
As for your contact list I don't use Eircom.net but make sure your contacts were not uploaded using their e-mail address only.
Each contact should be inserted with their First and Second name as well.
That way as you type the name ( and find out what name the system "prefers" you to type, the optional names offered will reduce down to a few close to your intended name.
In my system - which is Thunderbird, I still get more than the address block can let me see all at once, so I scroll down to the right one.
Its basically the old adage in working with any filing system - you set if up for ease of retrieval: quality in, quality out.
It takes a bit of work and time, but I've found that there is no substitute for doing it.
Saves huge amounts of time in the long run.