I want to know the following sentnce is correct in point of grammer and concept or not ?"?

Question

We plan to take action with assurance and on the base of systematic manner ,so we apologize for our delay to reply to your email because of the above mentioned reasons.

Answer 1

Hi, no offense because it is obvious you are trying, but first and foremost, you are using circular logic here and it makes the sentence appear to be convoluted and confusing.

1. What does "on the base of systematic manner" mean?  That makes no sense in English.

2. "we apologize...because of the above mentioned reasons."  There are NO reasons given for your delay above.  Are you sick, on vacation, or have a high volume of email requests to return?  You don't say.

Be as clear as possible and try to avoid run-on (very long) sentences.  

Are you trying to say something like this:  "Due to the high volume of emails we receive, we apologize for any delay you may experience.  Please be assured we answer all mail in the order in which it was received.  Thank you for your patience."

Answer 2

It's not quite correct and sounds rather stilted - I suggest the following:

We apologize for the delay in our e-mail caused by the above mentioned reasons and assure you that we will take systematic action to fix the problem.