Unbounded "TM" replacement with "™" in email text (ignores word boundaries)

[sermelipharo]

Bug description:

In the email newsletter system, plain text sequences of "TM" are being automatically replaced with the trademark symbol "™", even when "TM" appears as part of a normal word and not as a trademark marker. For example, a word like ATMOS is incorrectly displayed as A™OS.

Expected behavior:
"TM" should only be replaced with "™" when explicitly intended (e.g., following a product or brand name, usually in superscript or with proper markup).

Actual behavior:
The replacement is applied indiscriminately, causing unintended symbol insertion in the middle of words.

Impact:

• Words containing "TM" are broken or distorted. Currently only HTML abbreviations is affected due to capitalised case.
• Reduces readability and may confuse readers.