10,000 character limit on the Allowlist

Hi Team,

I am really disappointed with the 10,000 character limit on the allowlist for Zendesk access control. The way we have set up our Zendesk is to only allow emails from the customers in the allowlist. We add our customer domains in the allowlist for the same reason. The problem now is we have 15-20 customers that need to be added to zendesk on a monthly basis and we don't have any character space left in the allowlist. 

The only solution from the Zendesk support team is to trim the sub-domains, but we hardly have any customer sub-domains in the allowlist. The only solution I can think of is to set our zendesk access to open which means we are more vulnerable to spam emails. This is not our preferred option. Is there any chance we can increase the character limit on the allowlist?