I am running a number of hosted exchange to M365 migrations at the moment. As a part of this process, I need to update the max send and receive size in Microsoft 365s Exchange Center.
Normally this is simple, you can access the settings and change it without issue. However, I have a tenant where the options to do this are greyed out and can't be changed. I have tried with powershell using the exchange online management shell also but get the error:
Set-Mailbox : A parameter cannot be found that matches parameter name 'MaxSendSize'. The command runs fine on other tenancies without issue.
Note I am also a global admin for all the tenancies too. I figure there has to be a setting or config item somewhere stopping me from doing this but I can't for the life of me figure it out. Has anyone run into this kind of thing before? Any ideas on resolving it?
