australia
The commonwealth and all states and territories have enacted uniform legislation regarding Electronic Transactions. The relevant section here is 14A.
If the email address is one that has been "designated by the addressee" then it has been received "when the electronic communication becomes capable of being retrieved".
If it is not a designated address then, in addition to the above, the recipient must "become aware that the electronic communication has been sent to that address."
Both of which are subject to other agreements that the parties may have made such as, for example, certain correspondence being by mail or by hand.
So, for your example, you would need to check the policy to see if there is a specified manner by which notifications have to be made. If so, that's how you have to do it.
If not, is there a designated email address for such communications? The courts have held that addresses that are advertised (e.g. on a website or letterhead) or actually used for communications between the parties are prima facie designated. So sending it to addresses that have sent stuff to you is pretty safe unless it is clear that they are not designated. For example, if you receive a reply saying the address is not monitored or if the email is something like noreply@domain.com.
As a real-life example, I had to decide in an adjudication whether certain documents had been received by the Respondent. The facts were the Claimant had emailed them to an address the Respondent had routinely used for communication but because one of the attachments was a Word document, the Respondent's virus protection had deleted it 1.6 seconds after it arrived without notifying either the Claimant or the Respondent. So, what do you think?
Yes, it had been received. Not only was it "capable of being retrieved" it had been retrieved, albeit by the Respondent's automated virus protection rather than a person. In essence, it was no different than if it had been a snail mail letter that had been placed in the letter box and thrown out with the real estate flyers.