Hello, In the meantime I found a workaround.
Instead of 20 px for padding in blocks, I put 10 px of padding and 10px of border width (with same color as background), so it works well on most programs. Outlook can read the border: I have just a narrower border.
It is not a good time to give you access to the site, as we are launching the new edition of a festival.
However, I can send the code of the problematic template and my the temporary solution, by sharing the link of EmailOnAcid results.
Let me know if it's ok anyway, I'll send it privately
Thank you
Best regards