Read a bunch of VCF vCard files and build a csv with usermail-groups mapping
This is a small utility I made to export contacts that were into an RoundCube WebMail account and I needed to import into Mailchimp. Contacts were stored into groups in RoundCube but the group field was not exported (maybe it's possible in future versions of RoudCube, but mine was pretty old).
What I did was export each group one by one into different vCard (*.vcf) files and then run this little utility to generate a csv file that contained two columns: email and groups. Groups column contains a comma-separated list of groups into which the email belongs.
The csv format generated can be easily combined with your existing contacts (e.g.: using Excel's VLOOKUP function). Or you can fork and modify as you need.
An example formula I used for this:
=VLOOKUP(A2, contacts_table, 2, FALSE)
Enjoy!