[neomutt-users] [help request] How can I change my from address depending on the sender?

[laalsaas+nmutt at systemli.org]

I'm trying to make neomutt automatically use a different From-address
when I'm sending mails to a specific address. I tried just appending the
following line to my neomuttrc:

send-hook "~t ^~mil\/sxmo-devel at lists\.sr\.ht$" 'my_hdr "From: laalsaas+sxmo at systemli.org"'

This gives me an error when I start neomutt:

Error in /home/philipp/.config/neomutt/neomuttrc, line 16: No Context
source: errors in /home/philipp/.config/neomutt/neomuttrc

I have two questions:
Is this even the right approach for reaching my goal?
and if so:
What am I doing wrong?