The fix in the email template seems easy enough... see below. thoughts?
Email template: Email Wrapper
Before:
<a href='{setting="base_url"}' style='text-decoration: none; color: #262e33; border: 0;'>
{{$imgDims=NULL;}}
{{if \IPS\Settings::i()->email_logo}}
{{try { $imgDims = \IPS\File::get( 'core_Theme', \IPS\Settings::i()->email_logo )->getImageDimensions(); } catch( \Exception $e ) {} }}
{{endif}}
{{if $imgDims}}
<img src='{file="\IPS\Settings::i()->email_logo" extension="core_Theme"}' alt="{setting="board_name"}" width='{$imgDims[0]}' height='{$imgDims[1]}' />
{{else}}
{setting="board_name"}
{{endif}}
</a>
After:
<a href='{setting="base_url"}' style='text-decoration: none; color: #262e33; border: 0;'>
{{$imgDims=NULL;}}
{{if \IPS\Settings::i()->email_logo}}
{{try { $imgDims = \IPS\File::get( 'core_Theme', \IPS\Settings::i()->email_logo )->getImageDimensions(); } catch( \Exception $e ) {} }}
{{endif}}
{{if $imgDims}}
<img src='{file="\IPS\Settings::i()->email_logo" extension="core_Theme"}' alt="{setting="board_name"}" width='100%' />
{{else}}
{setting="board_name"}
{{endif}}
</a>
The key change being to set width to 100% (and delete the hard coded height and width). Height will then auto calculate.