Make Message warn about invalid addresses

* lisp/gnus/message.el (message-check-recipients): Warn about
invalid email addresses (bug#32639).
1 job for master in 66 minutes (queued for 2 seconds)
Status Job ID Name Coverage
  Test
failed #3423
test-all

01:06:00

 
Name Stage Failure
failed
test-all Test
Makefile:319: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:294: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:959: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1