The max length for USPS first class international packages was 24". But when I tried to ship a package yesterday, the message "First-Class packages cannot exceed 22" x 18" x 15"". came up. It would not allow me to ship a 24" long package. I went to the post office and was able to ship it. Is this a new restriction from USPS, or from shipstation? No one seems to know what is going on.
Confirmed with Shipstation, they do not ship packages over 22 inches in length anymore for USPS First Class International mail. You can go to the USPS website and use click-n-ship to mail a package up to 24 inches with First Class International mail. I don't know why shipstation made the change?