module ActionMailer::MailHelper

def format_paragraph(text, len = 72, indent = 2)

# => " Here is a sample text with\n more than 40 characters"
format_paragraph(my_text, 25, 4)

my_text = 'Here is a sample text with more than 40 characters'

+indent+ equal two spaces.
By default column length +len+ equals 72 characters and indent
Returns +text+ wrapped at +len+ columns and indented +indent+ spaces. 
def format_paragraph(text, len = 72, indent = 2)
  sentences = [[]]
  text.split.each do |word|
    if sentences.first.present? && (sentences.last + [word]).join(" ").length > len
      sentences << [word]
    else
      sentences.last << word
    end
  end
  indentation = " " * indent
  sentences.map! { |sentence|
    "#{indentation}#{sentence.join(' ')}"
  }.join "\n"
end