Is an Iphone Secure?

One of the things stopping me from getting an Iphone is what appears to be a lack of secure email (at least in my preliminary research).   For example, I think an OpenPGP is great and I use it often in thunderbird (more on that here).  But If I send a PGP encrypted email to someone who would otherwise be able to open the email with OpenPGP/Enigmail setup on Thunderbird, they won’t be able to read it on thier Iphone.

Any of you have experience with Iphone email security?  Please share your thoughts in the comment section.