We have a set of canned responses specifically formatted for chats and others that are specifically formatted for emails.
When doing the email canned responses I made sure to only use the formatting tools within <g class="gr_ gr_34 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling ins-del multiReplace" id="34" data-gr-id="34">purecloud</g> and have did not get a problem
If you have a screenshot of the canned response, and one then placed into an email I would be happy to show you what mine look like
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Lawrence Drayton
OVO Mobile (My Mobile Data)
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