I have to disagree though on the Priority shipping for INTL customers. To me, they're more reliable than First Class mail. I'd pick Priority Mail over First Class.
The tracking # is helpful, and while it doesn't offer detailed tracking once it leaves the country, it can still be traced if it got lost or delayed. Just need to call USPS and they''ll start a trace/conduct an investigation/request status from the receiving country if it's been delayed for more than 10 days and recipient still hasn't received it. .... and more likely the package will be returned to you if it's undeliverable!
If after a trace, USPS still can't find the package and your package in insured, you get a check $$$ from USPS (after filing a claim).
First Class Mail is "hope to god it doesn't get lost" shipping. If you're just shipping something worth a few dollars, it may be worth the risk but when I'm shipping anywhere from $300 to $1000 worth of stuff out the country, I just couldn't take that risk.
I understand USPS needs to raise rates. But my beef with this is the amount of increase ... almost 60% for Flat Rate Priority Small package. That's nuts.
@Crossroads. I use Endicia.com, you may want to check them out also. It runs natively on OSX too.