MYOB has a setting in the Preferences section under the Emailing tab called "When Emailing Invoices".
There is an option you can select which is to have a link in the email to the invoice as well as have a PDF copy of the invoice attached to the email.
This is a great feature and I have it as my setting. Only trouble is that the feature doesnt actually work and invoices are emailed with NO PDF attached !!!!
I contacted MYOB support and rather than saying this is a bug that needs to be fixed, apparently I need to suggest a product enhancement here so that MYOB might consider if it is worthwhile to fix a feature that already exists but doesnt work...