Whats the best way to do email validation?
Using Jamroom
Quote: mailgun activation or the kickbox activation
I assume you mean 'verification' and not 'activation'?
You don't have to use either. Jamroom will send an 'activation' email anyway in the hope that the registrant receives it and activates his/her account.
The advantage of verifying an email first is that MailGun or KickBox will verify/validate that email and JR will not send it if it fails their tests. This lessens the chances on email bounces which could get your site tagged as a spamming source.
I'd recommend using MailGun validation. Its free and as all your emails are being sent via MG anyway, let them be responsible for it all!!