Please email tech support (email@example.com or opena ticket in the support portal) with details regarding missing email or false positives AFTER you have whitelisted the sender's domain or email address using your webmail or account portal (depending on the system you are on). Then have the sender test and verify that after they are whitelisted (Trusted Senders) you are still not receiving their message(s).
Send us the following -
Date/Time it was attempted:
Using this information we can research and provide more feedback about how to ensure delivery or correct the issue causing the messages to be blocked. Typically there is an underlying reason related to the sender or their server's configuration or reputation.