How can I send email to multiple contacts linked with one lead?

I’ve added a lead and few contacts linked with that lead. Now, I want to send email to those contacts but the To list is showing blank. I made all contacts email id as primary but still it is not showing in the To list. Can I do something which can append all the email ids of a particular lead using comma separated in the To list?

Does the user have permission to send email and read the contact’s info?

What happens if you start typing the associated email address, does it populate the to field?

The to field does take a comma-separated list.

What docType are you trying to send?