strange characters showing in email

Hi Alex.??Thanks for your Advanced Order Export plugin. It matches exactly my customer’s needs.??

Alas, one thing is a bit of a puzzler: My customer uses his iPhone or iPad to receive the daily updates sent by your plugin. Whereas I see a normal E-Mail with text and an attached file, my customer gets loads and loads of text: either special latin characters or chinese (?) characters. ??

What can I do that my customer gets a standard email? Is there a switch to plain email format somewhere?

??Kind regards,?
Stefan?

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