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 > New group.

Group your Mail Contacts on the DingTalk desktop app so you can send to multiple recipients at once and keep contacts organized by team, project, or relationship.
icon in the upper-right corner > Mail Contacts > click … next to Contacts > New group.
