Check sending email address before sending

[inputchip]

I use multiple accounts in Outlook and therefore send from many different email addresses. I want to give a warning box if I am sending from an address I should not be sending from. I have two addresses that I should never send from (they are receive only accounts. I do not want to accidentally send from these accounts.

[inputchip]

I believe using a string comparison (StrComp) and Item.SenderEmailAddress is what I need. However I can't seem to get it to work.
Here is my current attempt for giving a warning for a single email address.

I am trying to post my attempt below, but it is not letting me post as it says it contains links (when it doesn't).

[inputchip]

https://pastebin.com/bpfa1yXc