I've posted this problem to drupal.org's forum(http://drupal.org/node/100792), but I couldn't get the solution. So I'm posting it here again to see if anyone can help. The question I posting is as pasted below:

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I am using TinyMCE + IMCE to insert photos to newsletter. When I copy&paste the template for newsletter to TinyMCE window, absolute URL is converted into relative url.

I thought this may be an issue with TinyMCE, so I googled and found out TinyMCE has the option to enable/disable relative uls conversion:
http://tinymce.moxiecode.com/punbb/viewtopic.php?pid=6134

However, when I saw the setting in tinymce.module, it was already disabled by default (line 493):
$init['relative_urls'] = 'false';

So I thought this conversion is done by IMCE, but I could not find relevant information or a way to fix it.

If you know how to solve this problem, please let me know.

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I got some advice from the developer of IMCE, but it did not solve the problem. Even if I enter absolute paths manually, it still gets converted into relative paths once a newsletter is reloaded by pressing 'Preview'. I still think it's TinyMCE that's doing the conversion, but I cannot find / think of any way to stop it. Any advice / suggestion will be greatly appreciated.