SPF Records - Looking for Guidance.

[#1]

My company recently has had a slew of requests to allow certain third parties to send email on our behalf. All was fine up until we hit the RFC limitation of 10 objets and we are still receiving requests.

I thought I might be able to chain SPF records together (i.e. have spf1.domain.com which would call spf10.domain.com, spf11.domain.com, and spf12.domain.com and all the records therein. Then I would do the same for spf2.domain.com and spf3.domain.com). However, this failed the check on mxtoolbox.com stating there were too many objects within the spf record.

Right now it looks like having my main spf.domain.com record will be able to chain spf1, spf2, and spf3. However, after that I am out of room... Is there a better way to do this? What if I have 10 more companies that need to sell mail on the behalf of my company?

Thanks.

[#2]

You could try creating "child" SPF records with up to 10 entries in each, then use the "incude" option to load them into the main "parent" record. There's a good example here:

https://help.blacknight.com/hc/en-us/articles/212512389-Creating-large-SPF-records-with-many-entries