Here's why:
* Redundancy: "Each" and "every" mean essentially the same thing, making the phrase unnecessarily repetitive.
* Wordiness: "Each and every" is a longer and more formal way of saying "all".
* Clarity: By removing these words, the sentence becomes more concise and impactful: "Please give your regards to all former students."
The revised sentence is shorter, clearer, and more direct, conveying the message effectively without unnecessary words.