It is no longer possible to email Virgin Mobile.
You can use the link here: Help and Support - Contact Us
Or calling 789 from a Virgin mobile is free.
Or calling 0345 6000 789 from any other phone is charged at standard rate & will be included in any bundled minutes.
If it's a simple query that you want to contact them for you could try asking on this forum. Someone may have the answer.
I hope this helps,
If you want to say thanks > click 'Kudos'.Answered your question? > click 'Mark as Helpful Answer' also.