IP address on XBL Blacklist (Out going server response)
I think that the IP in question is the IP of your mobile device or the NAT router that your carrier uses. De-listing won't help here and would in fact just be counter-productive.

Anyway, if you use SMTP with authentication you should never see this message with an SMTP server that is configured proper. Assuming that anonymous SMTP is not practicable or even possible with Android devices, there is nothing you can do.