Delays in mail deliveries

[Damian]

>> A suggestion was to whitelist the sender address (at the example below: no-reply at sharepointonline.com), but we fear that this 
>> (or other similar) commonly used sender address may be deceptively used in third-party phishing/malicious mail which will then 
>> get through unprocessed/unfiltered.
> 
> You are worried about scams and phishing, but SPF and DKIM checks should protect your server from those attacks, shouldn't they?
Concretely: @author_to_policy_bank_maps.