Gnus: How to easily change "From:" from the default to a second account's address?

[Marius Hofert]

Hi,

If I want to create a new message with "m", it shows my default email address 
in "From:" I specified with
(setq user-mail-address "my.name@uni.edu")
Since I have a second account (googlemail), every once in a while I would like 
to hav "From: my.name@googlemail.com" instead of "From: my.name@uni.edu". So 
far, I deleted the entry and typed in my gmail account's address. Is there a 
simpler way?
I also tried to hit "m" when the point is on my gmail account in the *Group* 
buffer, but that did not open a new message with the corresponding "From:" 
address... 

Cheers,

Marius