Top Malaysian hosting service provider stops forwarding emails to Yahoo!, Gmail, Hotmail, Streamyx, TMnet and others

This writer has just been informed that Exabytes will no longer permit email forwarding to the following free email providers:

Yahoo!
Gmail
Hotmail, and other popular mail servers

as well as local ones such as tm.net.my and streamyx.

According to my informer, this move is due to "free email service provider having applied stricter anti-spam policy in their mail servers."

Meaning, if they detect any of Exabytes customers setting their forward emails to these servers, and the account receives lots of emails, the free servers will consider it an attack on its servers and will stop future forwards, including those from Exabytes itself to the account holders.
And the result, blacklist Exabytes mail servers from sending mail to them, ie causing legitimate email to be blocked.

I wonder why this is happening to Exabytes when other international hosts also face similar problems.

I do know of a Canadian host as well as a San Franciso-based hosting service which are widely used by Malaysians who have email forwarding to the said services and are not experiencing any problems that made them change email hosting policies like what Exabytes just did.

Perhaps someone out there care to explain?