Why do you want to do this? In some common cases, you have (in my opinion) better options:
Please ask on the NetBSD/amiga mailing list. Somebody there should be able to help you. Note that the port maintainer reads this, too, regularly; so if nobody else knows, he can also answer. However, _if_ somebody else knows, you'll get your answer faster.
Check in the bug database, whether it is a known problem.
If it is not a known problem, Open a new entry in the bug database. This way, more people than just the portmaster will be able to work on the problem, and if they get distracted, somebody else will be able to pick up from where the others left.
A lot of people have contributed. You better thank all of them on the NetBSD/amiga mailing list.
If you still need to contact the NetBSD/amiga port maintainer directly (e.g., you want to donate hardware or information to help the port, or provide new software), the generic address is port-amiga-maintainer@NetBSD.org.