• UPS is my preferred and recommended shipping service. UPS has an on-time money back guarantee for select services, including ground shipping. They tell you exactly the day your package should arrive, not an estimate such as 2-3 days. With breast milk shipments, it's important to set up the exact day to plan to be home.
• USPS is the shipper I use for overnight packages. They have the best overnight rates and they do guarantee delivery for overnight shipments.
• Plan ahead and get to the shipping location at least 30 mins early. If you're cutting it close to the cutoff times for shipments that day you may have delays or a line ahead of you.
• Shipper may have different cutoff times for air and ground shipments. Do not go by the shipper's hours of operation, they are not usually the same as the shipping times. If you miss the cutoff deadline, then you have to wait until the next business day or maybe you can find another location close enough that is still taking packages as the collection driver hasn't gotten there yet. I highly recommend not taking the risk.
If you still have any further questions or if I have missed something useful that should be included, please let us know!