embedding newlines in procmail actions

Era Eriksson wrote, where "$COMMAND" included embedded newlines,

| # You might have to muck with SHELLMETAS here
| 
| :0bw
| * ^Subject: xxxxx
| | eval "$COMMAND"

Procmail will complain that there is no executable named "eval" to be found
in the directories in $PATH, but this time the solution is not to change
$SHELLMETAS to suit the action but rather to change the action to suit
$SHELLMETAS:

  :0bw
  * ^Subject: xxxx
  | eval "$COMMAND" ;

This is a standard trick for using shell built-ins.