Email Source: Mailgun

Homepage: http://www.mailgun.com/

This source is known to forward email

forwarding notes:

Mailgun can process incoming email and then forward it on to a final destination. Depending on the processing, DKIM can survive.

Capable of generating DMARC compliant email for others

Yes

Mailgun will send DMARC-compliant email with just a little bit of configuration: https://help.mailgun.com/hc/en-us/articles/360026833053-Domain-Verification-Walkthrough

Capable of signing email with DKIM for others

Yes

To configure DKIM, see: https://documentation.mailgun.com/en/latest/quickstart-sending.html?highlight=verify#add-sending-tracking-dns-records

Capable of sending SPF compliant email for others

Yes

To configure SPF, see: https://documentation.mailgun.com/en/latest/quickstart-sending.html?highlight=verify#add-sending-tracking-dns-records