Correct way to offer customized thunderbird versions

Hi all,
I would like to create and distribute a customized Thunderbird version, 
if possible based on a portable version of thunderbird. All changes can 
be done by creating a custom profile. What is the best/easiest way to 
do this without violating mozilla trademarks or other rights? 
Specifically, I would like to include a custom theme, some pre-set 
account settings for a specific nntp server, and preinstalled 
extensions. Is it OK just to install a portable thunderbird, set up the 
profile, pack the directory containing all binaries and profile data up 
and distribute that? I want updates to work so I would like to avoid 
creating a completely custom product like icedove.

I would like to make it as user-friendly as possible, i.e. installing 
by a single installer.

Sincerely
Jan

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