Volusion is capable of sending DMARC compliant email because they support custom SPF and DKIM configurations that achieve DMARC alignment. Volusion is an Email Marketing Platform and is often used by Marketing and Product.
Contact Volusion to inquire on DKIM capabilities.
Add 'include:emailsrvr.com a:smtp5.volusion.com' to your SPF record. However, beware this will pull in a lot. Our data indicates you only need the IP from the 'a' mechanism, which is '162.219.105.64'. That IP might change, but if you place 'ip4:' instead of 'a', that won't use an SPF lookup, unlike 'a'. Contact Volusion and ask for an optimal solution. You can also visit the following article for more information: https://helpcenter.volusion.com/s/article/SPFDKIMandDMARCRecords