White Listing a email address in UTM 9.2 that sends your domain mail from external host

I am from Pepkor South East Asia / Best and less / Harris Scarfe

we are new to the Sophos UTM 9.2

We use a service called Clarizen

the website sends us emails from Clarizen@harrisscarfe.com.au

We are harrisscarfe.com.au, so i had to white list them

I used the following document to white list clarizen as per clarizen recommendation. I got this PDF list when logging a job with them

images.messagelabs.com/.../Subnet_IP.pdf

My infrastructure manager believes this is white listing too many IP ranges.

I put in these exceptions in to our UTM as per documentation to white list IPs

216.82.240.0  255.255.240.0  /20  216.82.240.0 – 216.82.255.255 
67.219.240.0  255.255.240.0  /20  67.219.240.0 – 67.219.255.255 
85.158.136.0  255.255.248.0  /21  85.158.136.0 – 85.158.143.255 
95.131.104.0  255.255.248.0  /21  95.131.104.0 – 95.131.111.255 
46.226.48.0  255.255.248.0  /21  46.226.48.0 – 46.226.55.255 
117.120.16.0  255.255.248.0  /21  117.120.16.0 – 117.120.23.255 
193.109.254.0  255.255.254.0  /23  193.109.254.0 – 193.109.255.255 
194.106.220.0  255.255.254.0  /23  194.106.220.0 – 194.106.221.255 
195.245.230.0  255.255.254.0  /23  195.245.230.0 – 195.245.231.255    
103.9.96.0 255.255.252.0 /22 103.9.96.0 – 103.9.99.255

Can you confirm i have done the right thing or is there a better way to white list Clarizen@harrisscarfe.com.au in our UTM,  I think the only other way is a stupid big SPF update

Attached is proof that the emails come from a big wide range of IP addresses.  

I need confirmation i have white listed appropriately or if there is a better way