Mails forwarded take more than 10min to be delivered

Mails forwarded take more than 10min to be delivered

We have just migrated some of our accounts to Zoho and we want to move the rest soon. Some of our employees receive the corporate mail in their personal mail and we want to keep supporting that.

In our tests the mail forward functionality is really slow (15 min long). This is too long for our needs. Is it a temporal problem? What is the normal time to be sent?

This would prevent us to migrate to Zoho which would be a shame as we have invested quite a bit of time moving here.

Thank you for your help, David