If you are unable to collect your marriage certificate yourself, here is a sample marriage certificate authorization letter.
To [Recipient name]
Dear, [Recipient name]
I, [Your name] hereby authorize my mother [Your mother’s name] to collect my marriage certificate on [Date]. I herby give her the right to sign any documents on my behalf regarding the collection of my marriage certificate as I cannot visit your office due to [Reason].
My identification proof as well as my mother’s documents are attached to this letter for further processing. I authorize her to fulfill the necessary requirements in my name.
Any inconvenience caused by this is regretted. Thank you for your cooperation.