Client's DNS is managed by Office 365. Office 365 helpfully creates an SPF record:
TXT @ v=spf1 include:spf.protection.outlook.com -all 1 Hour
Even extra helpfully, this is automatically generated by Office 365 and can't be changed apparently. All I want to do is include Mandrill, but it looks like I'm SOL.
Apart from moving DNS management to another host (which would be painful, but doable), have I got any options?