PSA: Sending emails going to UTF-8 only

Magnus Melin mkmelin+mozilla at
Mon Aug 10 09:43:44 UTC 2020

We intend to finally address bug 862292 and use UTF-8 for all outgoing 

Sending in other charsets had previously, many years ago, been kept on 
concerns over the Japanese market where apparently some smart-phones at 
the time did not like UTF-8. Therefore we've had a localizeable pref for 
what to use as default charset. However, since 2017 even the Japanese 
locale has opted to have that set to UTF-8. Gmail has also used UTF-8 
only at least for 5 yrs, so we can assume it should not be a problem.

Getting rid of encoding to other charsets will save us some needless 
code complications, and also ensure maximum compatibility reading these 
mails in the future.

This change will not be backported, it's only about trunk going forwards 
and for the next major ESR (TB90?) release in 2021


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