Can I edit the names in the dropdown list when I fill in the recipient's To: field?

 I seem to have old information from long deleted contacts that show up in the drop down list when I am filling in the To: field for the recipient. I even have the name of the wife of a contact show up when she is not listed in the contact information at all. Where can I delete these old contacts and incorrect email addresses.

The list is populated from both Contacts and previous recipients history. You will find the latter in Menu > Tools > Settings > Mail > Compose > Recipients History, where you can either clear the complete history, or delete just the ones you no longer require.