In Google Docs, you can collaborate on documents but not emails directly; however, you can send Gmail messages from a Google Doc or attach it as an email attachment. To compose an email in Google Docs and send it via Gmail, follow the steps to draft and send an email template or attach a file. Alternatively, you can share a Google Doc in an email as a file preview or directly share it with others using the Share options. You can also automate this process by connecting Google Docs to Gmail using Zapier, which allows for automated workflows and no-code automation tools.