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How to resolve error-20950and what is the character limit for messages ?
obvious reason is if the <Body> node has more than expected
characters, it will throw the error. The other reason is you are using a
version lower than 653 which also doesn't allow character limit over 2000
Now the next question is what is the expected characters count that can be specified in the <Body> node ? Below are two use cases which will help you understand the character count limit.
1. Ask Seller Question : If the message was created when the use clicked on 'Ask Seller Question', AddMemberMessageRTQ api allows you to specify 4000 characters in the <Body> node. Anything more than that will throw the error.
2. Contact eBay Member : If the message was originally created by 'Contact eBay Member', AddMemberMessageRTQ api allows you to specify 2000 characters in the <Body> node. Anything more than that will throw the error.
In order to find the message type i.e. 'Ask Seller Question' or
'Contact eBay Member', you need to execute GetMemberMessages api request and
look for MailMessageType in the api
response. Here is the doc link for the same : http://developer.ebay.com/DevZone/XML/docs/Reference/ebay/GetMemberMessages.html#Request.MailMessageType