unwanted sender header via smtp submission [Was: Multiple Identities: Anonymity]

[hede]

Hi,

It seems the MUAs add those headers. At least in my case. 

I've added a line "/^Sender:/  IGNORE"
to /etc/postfix/header_checks.submission and now the header has vanished.

But that's not a solution, it's just a test. Because it will even get removed if the header is desired and not set by accident...

Yet the question how to suppress this in roundcube and android k9mail is still open.

regards
hede