2 suggestions:

1.  Use interpolation in the string instead:
```ruby
:body => "on the Superbox IPN forwarder, there is no queue set up for this function: '#{method_called_by}' for your developer_id"
```
1,  Include what the system thinks is the `developer_id` so the developer doesn't have to figure it out himself:
```ruby
:body => "on the Superbox IPN forwarder, there is no queue set up for this function: '#{method_called_by}' for your developer_id '#{developer_id}'"
```