"MessageLabs has now intercepted 1.2 million copies of W32/Mydoom.A-mm. The company is processing between 50,000 and 60,000 copies of the worm an hour. To date, the worm’s peak infection rate is 1 in 12 of all email scanned be MessageLabs. So far, the worm has been seen in 168 countries." link

The Tech Report - Worms bores through fabric of 'net | W32.Novarg.A@mm | Mydoom worm fills inboxes with zip file(s). | update your av software now - you do have av software don't you? | 'Novarg' or 'MyDoom', the latest mass-mailing worm to infest your in-tray is spreading at the same rate as SoBig - The worm also targets the SCO Group's corporate website | more links Mydoom Worm: The Next 'Big Evil' On The Net" | "today's windows virus". [slashdot.org*] | sample message. | more info.

presumably if your company have antivirus software on your email server and it's up to date (and it checks all your emails) then you should be okay. likewise with yahoo / hotmail which should theretically be able to stop hotmail / yahoo users from recieving this...

* "I brought a new Iron the other day and in capital letters in the instruction book I was told to never iron clothes while I am wearing them and that while I could use the shot of steam while the iron was in an upright position I should not forget the previous instruction about not ironing the clothes I'm wearing." link.