We have faced with issue related to some form POST limtation (429 error). Is there any way to increase this limit with some very big number per minute? The best case scenario would be to remove limitations for few ip addresses.
We have rate limitation coming from the same IP address to prevent spamming. If you are doing a large integration, you should be using the SOAP API or the REST API which is coming soon. Here is the doc for SOAP API - http://developers.marketo.com/documentation/soap/