Customizable Tenant-level Recipient Limits

@Manoj Kumar - The max allowed in the service is 1000. So even if both your MailUser setting and your TransportConfig (tenant-level) settings are Unlimited the EXO service setting of 1000 is then used. As noted in the article above, "Unlimited" means fallback to the next higher level setting: 

"Now, just because it says ”Unlimited” doesn’t mean that it is. It actually means “fall back to the next higher level setting,” which for a mailbox or mail user is to fall back to the value on the tenant-level setting, the tenant’s TransportConfig MaxRecipientEnvelopeLimit setting. And “Unlimited” on the tenant-level setting, in turn, means to “fall back to the Exchange Online service-level setting” – which in the Exchange Online multi-tenant environment is currently 1,000 recipients."

Hope this helps!