I started using Thunderbird several months ago. I use Windows10 and Edge; using the settings advised by optus. Optusnet is my email server. With some difficulty I downloaded my address book via a CSV file. Emails to or from Yahoo addresses do not arrive. A sent message records as having been sent and is in the sent box but is not received by the addressee. Arriving emails do not arrive from Yahoo. All other email addresses appear to be delivered ok. I have double checked all of communication settings. Please advise.