Quote from the Mauritius Civil Status Division website:
"11. How do I conduct genealogical research?
Through an application process, provide information pertaining to self and known filiations to an Civil Status Officer at any Civil Status Office
12. How long does it take to obtain relevant requested copies?
For record available on the database, Birth Records from the year 1920 to date, and Death and Marriage Records from 2001 to date, are available on Civil Status Database, these Civil Status documents will be delivered instantly.
However for,
Birth Records: 1861-1919
Death records: 1950-2001
Marriage Records 1940-2001, extracts are delivered subject that accurate information is provided by applicant."
Source:
https://csd.govmu.org/Pages/FAQ.aspx
Postal address here:
https://csd.govmu.org/Pages/Contact-Us.aspx
Email address (unless it's the one that you've already tried):
[email protected]
Quote from their Customer Charter:
"Any person should produce a proof of his/her identity and a stamp of the value of Rs 25 to obtain a copy of . . . birth or marriage certificate for his/her ascendants or descendants".
So it looks like you'll need to find a way to send proof of your identity (perhaps a copy of your passport?) and return postage. Postal rates are here:
https://www.mauritiuspost.mu/document/tariff2021.pdf
(Rs100 = £1.83)