In Prison Break season 5 episode 8, Michael, Lincoln and Sheeba come to the house at Ithaca where Sarah and Jacob lives. After getting off the vehicle, Michael suddenly sees their post box named Ness 1990. Then suddenly Michael leans to the drain alongside the road near post box and says that's why Sarah didn't get any of his letters. How did he know already to where to look at exactly? in flashback scene, after that, it shows that Jacob opens a letter every day and put Michael's signature origami swan into the drain pipe. But how did Michael knew exactly that Jacob did it? It could be numerous reasons Sarah didn't get Michael's letters, or maybe she did get them but didn't had any intention or chance or doesn't know how to reply to them letters.

Is there anything I missed here or else how did Michael know exactly where to look at the first glance of the post box in front of Sarah's house?

In Prison Break season 5 episode 8, Michael, Lincoln and Sheeba come to the house at Ithaca where Sarah and Jacob lives. 

After getting off the vehicle, Michael suddenly sees their post box named Ness 1990. Then suddenly Michael leans to the drain alongside the road near post box and says that's why Sarah didn't get any of his letters. 

How did he know already to where to look at exactly?

In a flashback scene, after that, it shows that Jacob opens a letter every day and put Michael's signature origami swan into the drain pipe. 

But how did Michael know exactly that Jacob did it? It could be numerous reasons Sarah didn't get Michael's letters, or maybe she did get them but didn't have any intention or chance, or doesn't know how to reply to those letters.

Is there anything I missed here or else how did Michael know exactly where to look at the first glance of the post box in front of Sarah's house?

In Prison Break season 5 episode 8, Michael, Lincoln and Sheeba comes to the house at Ithaca where Sarah and Jacob lives. After getting off the vehicle, Michael suddenly see their post box named Ness 1990. Then suddenly Michael leans to the drain alongside the road near post box and says thats why sarah didn't get any of his letters. How did he knew already to where to look at exactly? in flashback scene after that it shows that Jacob opens a letter everyday and put Michael's signature origami swan into the drain pipe. But how did Michael knew exactly that Jacob did it? It could be numerous reasons Sarah didn't get Michael's letters, or maybe she did get them but dodn't had any intention or chance or doesn't knew how to reply to them letters.

Is there anything I missed here or else how did Michael knew exactly where to look at the first glance of the post box in front of Sarah's house?

In Prison Break season 5 episode 8, Michael, Lincoln and Sheeba come to the house at Ithaca where Sarah and Jacob lives. After getting off the vehicle, Michael suddenly sees their post box named Ness 1990. Then suddenly Michael leans to the drain alongside the road near post box and says that's why Sarah didn't get any of his letters. How did he know already to where to look at exactly? in flashback scene, after that, it shows that Jacob opens a letter every day and put Michael's signature origami swan into the drain pipe. But how did Michael knew exactly that Jacob did it? It could be numerous reasons Sarah didn't get Michael's letters, or maybe she did get them but didn't had any intention or chance or doesn't know how to reply to them letters.

Is there anything I missed here or else how did Michael know exactly where to look at the first glance of the post box in front of Sarah's house?