@Boca89, this depends which programm you're using, in Webmail you can enter the e-mail or keyword from the title in the "search" field, that's the easiest way. If the mail is already deleted, then of course you won't find it anymore. From the "thrash" folder it will be deleted latest 30 days after deletion form inbox. Or you can scroll down your mailing list, but this can take time, depending on the number of mail you have in your folders.
each other e-mail programm I knwo, has also such a search function.
Agus fágaimid siúd mar atá sé.