I'm having a bit of the same problems.I've looked in the FAQ and didn't see anything that would address this issue. I'm using a Nokia 6600 from T-Mobile and can sucessfully post an email post but when I use the LJ Email headers:
I leave lj-gallery as the faq notes say: You can specify what photo gallery you want your attachments uploaded into using the lj-gallery header. If unspecified, the default gallery is 'LJ_emailpost'. If you decide to move your images into different galleries in the future, the images posted in your journal will still work correctly.
But when I email a post with an image all the post will show is the tag headers.
My phone is also a symbian phone too.
Also, The previous comment about sending it as a 'slide' If I do that I can't add the lj email tag settings. I'm thinking if you make a post by email with a picture your leaving the tags in.
Thanks for all your help in advance.