I think for immediate family and grandparents its better to phone them, if you have reservations about telling them then wait until 2nd trimester to say something.

If its a fear of negative reaction waiting would seem like a good option but I would still do the right thing by ringing them. If they get rude you can always hang up. If they argue why they weren't told earlier you can say you wanted to wait to make sure things were on track first.

I personally don't think email for immediate family is appropriate for such joyous news. You should be so proud of what you are creating inside you surely thats worth a call?

Besides at least then they can't complain about being told over the email which is less personal, if you do the right thing thats all that matters

Best of luck,

Nae x