We use Content Builder with a custom HTML template (stated and saved as UTF-8) and several content blocks (all in UTF-8) which use AMPscript (lookup) to retrieve information out of Data Extension, which are populated by automated import jobs (which use UTF-8 CSV files).
Customers informed us that at some (not all) devices, umlaute in some parts of our emails look weird - surprisingly, not only the DE-based info (2), but also hard coded content blocks (1):
What can be the root cause for that? Which "corresponding drop down" are they talking about? I can't find any way to format the language of either the template, the content block, the Data Extensions or the email itself.