FireDrum Email Marketing supports full DMARC compliance.
Contact FireDrum for DKIM setup. Fore more information, visit: https://kb.firedrumemailmarketing.com/knowledge-base/setting-up-your-dkim-dmarc-and-spf-records/
Add 'include:mtas.firedrumemailmarketing.com' to your SPF record. For more information, visit: https://kb.firedrumemailmarketing.com/knowledge-base/setting-up-your-dkim-dmarc-and-spf-records/