It might be you - not them
Have a look and see what your Plain Text Settings are in Mail Sending Format
OE > Tools > Options > Send tab > Mail Sending Format > Plain Text Settings
Post back on here with settings you are using.
Galaxy Note 8 vs iPhone X
Awful clip art from 1994 is being tweeted every hour by a bot
iPhone X vs Samsung Galaxy Note 8
Les meilleurs navigateurs internet 2017