Single Send API - custom properties not working with template


We had our application running till Friday 10/14 without an issue from last 6 months. It uses Single Send API to send email to a contact.

Since 10/14, we have noticed that some emails sent through it are not merging custom properties submitted to API. I have debugged and all values are getting submitted properly to API. This is also not a consistent behavior. I created multiple email templates to play with it and noticed that as soon as I add a decimal value, some custom properties stop working. This was not the case before 10/14. We have not made any code changes and it have sent more 100,000 emails with it before.

Any help is appreciated.


Here is what I have in my test template –

Hello {{custom.ShortName}},

Market Average: {{custom.MarketAverage}}



and here is what we posted to API and got a 200 OK message –

“emailId”: “4453119641”,
“message”: {
“to”: ""
“customProperties”: [

  "name": "MarketAverage",
  "value": "3.55"
  "name": "ShortName",
  "value": "Western"
  "name": "Name1",
  "value": "Yahoo"
  "name": "Product",
  "value": "Used Car - 60 Mo"
  "name": "Amount",
  "value": "8000"



HI @Amit_Wadhwa,

Just wanted to let you know that our email team is working on tracking down the issue. I’ve opened a customer support case with your team and will reach out directly.