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I just realised that when I send letters etc to the US etc that i hardly ever sign and date the bottom of the customs label. How important is it to actually sign it? The date is on the stamp, so I guess that might be ok, but is there a chance im missing possible responses by it not even getting out of the country? Or if that was the case would they just get RTS?

Just tweeted Royal mail and they said it should be fine so long as the rest is filled in.