Paying for a "Operation restricted due to excessive usage"

Paying for a "Operation restricted due to excessive usage"

Hi,

I'm trying to upload several thousands of emails (6 accounts with a total of 25GB) using IMAP because import PST is limited to 60MB.
IMAP transfer with a few thousands emails collapses due to an append limit.
But when transferring 2.000 emails works fine... until message:
Operation restricted due to excessive usage
appears when checking mail folders and RUINS all the migration process, because this error disables Mail function for 30 or 60 minutes.

This is NOT SERIOUS for a vital software for a small business.

We have chosen Zoho CRM + Project + Mail + Meetings +... for to do our little business not for to have a lot of new problems.

WE MUST RETURN TO MS EXCHANGE AND OTHER APPS ?

Antonio Embid