Can we generate the Offfice 365 MX-Token needed for the MX-DNS-Record by ourselves?

Question

Hi there
As a hosting company we programmed a DNS-zone-editor in which our customers can edit their DNS-zone. A new feature we are offering is a so-called "DNS-Template-Service", in which our customers can select predefined record templates like GoogleApps
and then trigger by one click the installation of the predefined records.
We also would like to offer them "Office 365" as a template. According to this article https://support.office.com/en-ie/article/Create-DNS-records-at-any-DNS-hosting-provider-for-Office-365-7b7b075d-79f9-4e37-8a9e-fb60c1d95166#BKMK_add_CNAME we
understand that all we need to do is to add a couple of CNAME, TXT and SRV records which is great.
However, there is also an MX record with a dynamical component (the "MX-Token") that is required:
<MX token>.mail.protection.outlook.com
We understand that this token can be fetched by the customer from their office installation. However that would break the purpose of our templating system that is designed to work like an on/off switch.
So our question is if there is any way that our system could generate this token by itself since we have knowledge of the customers domain anyway.
According to some customers who already installed those records manually we can see some patterns:
Example 1: domain1.com results in an MX with a value of
domain1-com.mail.protection.outlook.com
This is easy: just replace the dot with a hyphen.
However for domains with hyphens in the name a special conversion is made and appended on the back of the first part: 
Example 2: domain-withdash.com results in an MX with a value of domainwithdash-com01e.mail.protection.outlook.com
Example 3: dom-ainwithdash.com results in an MX with a value of domainwithdash-com0i.mail.protection.outlook.com
Example 4: doma-in-withadash.ch results in an MX with a value of domainwithdash-com01bb.mail.protection.outlook.com
So what is the algorithm for this (probably bidirectional) conversion?
Thanks for letting us know and make it easier for our customers to use office 365 with their own domain name.
Regards
Lukas
Developer @ cyon GmbH

Answer 1

We actually spent the last 1.5h to reverse-engineer the pattern and (hopefully) found the right answer on how these hyphen-replacements are substituted.
* This functions generates a token as done in office 365
* @return mixed|string
private function getOffice365MxToken($domain)
$delimiter = '0'; // delimiter between the domain part and the hyphen replacement part
$token = $domain;
$hyphenReplaceToken = '';
// split domain string into chunks of 4 chars
$chunkSize = 4;
$chunks = str_split($token, $chunkSize);
// transform the hyphens (their position) in the domain name to an alphanumerical character string
$skipCount = 0;
$intOfA = ord('a'); // get the decimal value of the letter 'a' as start value
foreach($chunks as $chunk){
$digit = $intOfA;
for ($i = 0; $i < $chunkSize; $i++){
if('-' === $chunk[$i]){
$digit += pow(2, $i);
if($intOfA === $digit){ // if the value is a it means no hyphen was found
$skipCount++;
continue;
if (0 !== $skipCount) {
$hyphenReplaceToken .= $skipCount;
$hyphenReplaceToken .= chr($digit);
$skipCount = 0; // rewind skip count
if(strlen($hyphenReplaceToken) > 0){
$token .= $delimiter . $hyphenReplaceToken;
$token = str_replace('-', '', $token); // remove - from domain name
$token = str_replace('.', '-', $token); // replace dots with -
return $token;
Short-hand explanation: The pattern showed that the domain string simply gets chunked into pieces of 4 chars. For each setting at which hyphen(s) can be located at the index value (seen as bit mask 0124) is added up. The resulting number we get per chunk
then can be added to starting decimal value of the letter 'a' (97) and thus gives us another letter that substitutes the hyphens locations in this chuck. If no hyphen is found, the algo simply counts for how many chunks none were find and adds this up sa a
number.
These concatenated letters + skip-numbers then result in the replacement token that gets appended on the end of the domain name (hyphens removed, dots replaced with hyphens). 
Oh and yeah, between these two parts a '0' is added as delimiter.
That's it. I hope we got it correct.
Regards
Lukas @ cyon GmbH