From the Super Mario Wiki
Mr. E is one of two Dryites with blue clothing in Paper Mario. The name Mr. E is a pun on the word "mystery" which is probably why he stands out of the other Dryites with distinctive blue clothes. Mr. E partakes in a long chain of Letters Mario and Parakarry can optionally deliver by receiving a Letter from Koover. Upon acquiring this Letter, Mr. E reveals that his job is to ship various things out of Dry Dry Desert into other parts of the world; apparently, Koover had ordered some sort of item from him. Mr. E himself continues the Letter relay by having Parakarry take a Letter of his to Miss T. of Toad Town, who apparently does not even know him. Though she does not open it, making things unclear, Miss T. theorizes that this Letter expressed love, as she apparently receives love Letters from people she does not know often.
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