Steps
Open the DingTalk desktop app > click Mail in the left sidebar > click the
icon in the upper-right corner > Mail Contacts > click … next to Contacts > Import contacts or Export contacts.

Import contacts in CSV or vCard format into Mail Contacts, or export your existing contacts for backup or migration to another mail client.
icon in the upper-right corner > Mail Contacts > click … next to Contacts > Import contacts or Export contacts.
