MLS properties and letters of intent

[A Miller]

I am just starting to get into wholesaling properties. I want to use the MLS to send letters of intent for properties that have a high number of DOM, are estates, or where the listing description includes that the seller is motivated. I have found a realtor that I like and who understands what I am doing however he just informed me that in order for the letter of intent to be taken seriously, I also need to include proof of funding. He also stated that if he sends too many LOI's that I can't make good on, he could be subject to scrutiny by the board of realtors. Can anyone confirm if this is true? My understanding is that the LOI is simply a starting place to determine if a seller is truly motivated. I would appreciate any insight.