Nylas has more headers because the outbound server requires identifiable information when delivering email to their SMTP server. View the example below.
Received: from 316292377349 named unknown by gmailapi.google.com with HTTPREST; Wed, 19 Jan 2022 00:22:11 -0800 Received: from 86-91-255-117.opennet.kpn.net (86-91-255-117.opennet.kpn.net [126.96.36.199]) by api.nylas.com (Nylas) with HTTPREST id 57xktlb0e5v06k7wgvup5psls-0; Wed, 19 Jan 2022 08:22:11 +0000 (UTC) User-Agent: Nylas-nylas.com/18.1.0 X-Inbox-Id: 57xktlb0e5v06k7wgvup5psls-0
User-Agent value is required according to HTTP standards and protocol. It contains information from your application's name. This value is for provider reference in trusting IP addresses. The
X-Inbox-Id is equivalent to the Nylas
message_id value with an added
Nylas tracks deliverability results comprehensively. Additional headers don't impact the process.