Hi Beverly25
Yes you can do it through post.
I got married here in the UK, Jan. 2012- and I just registered our marriage, in Philippine Embassy London lately.
All the information and documents needed are in the Philippine Embassy website, also the form that you need to download.
Don't forget your marriage registration fee, and self-addressed stamped envelop.

As that happened to me- I forgot to send the fee
so it took them couple of weeks to process it. I got it in the end though..