It appears that your posts were added before there was a requirement for a metal base (post base/post anchor) to be placed between the wood and the dirt/ground. What you want is to avoid direct contact between the wood post and the soil.

I can't tell if there is an issue with the way your drain spout has been buried. I have zero expertise in this area - except for having my drain spouts buried as yours has been. However, I do know that mine are buried so that they are down hill from the foundation of the house.

I assume that the grading of your yard was done to keep water away from your foundation. Having the gutter buried between the post and the house seems like it would cause the water to run away from the foundation = towards the wood post. Add the lack of a metal barrier between the ground and the wood = rot.

There are ways to address the rot without replacing the entire wood post - depending upon how bad it actually is. You may be able to cut away the damaged bottom of the post + treat the remaining wood to make sure that no rotted wood has been left + add a metal base + a new piece of solid wood (or use Bondo to replace the rotted wood that you've removed).

However, depending on the extent of the rot, it might be best to completely replace the post for structural integrity.

"Not sure what to with the drainage?"

I'd start with making sure drainage drains.

Reading comprehension is a skill you should work on. Good luck.

You must be related to Klem1.
This is an advice and discussion forum not your personal forum. You must have a lot of time on your hands to take the time out of your day to criticize my post. Bless your heart.

Judging by the look of the pole, it would be better to replace it or cover it with thin stainless steel, but this will not last long. But drainage is a real problem here - if it is not directed properly, your problem will not go away. It may be worth checking whether the gutters are doing their job. I've gutters that have a self-cleaning system . Also, look at how the water flows during rain, and perhaps you will need to redirect the drainage.