If the email addresses for a mailing have been imported as "non-anoymous", then you can download the address list incl. SERIAL as follows:
- Invitation Mailings -> List of contacts
- Tab "Manage Addresses" -> "Download Mailing List"
This download will contain not only the email address for each SERIAL, but also detailed information on each entry.
Using any common statistical software, you can now merge this data into your data set, using SERIAL as key variable.