I receive the following message when attempting to send email from my computer:
Message could not be sent to the following recipients: [recipient's address] (550 - 550 5.1.0 Authentication required
What is going on? what do I do? It appears to have been sent by using my phone.
Can you clarify------are you trying to send from the phone or the computer? Why do you think it's being sent from the phone? %00 series errors usually indicate a problem with the recipient's email address or account.
Because it bounces back from the computer, but I have received replies from the phone. I don't know what %00 means. There are no problems with receipient's email, these are people and businesses i deal with frequently. I find that whenever there is a problem with email, it is inevitably Comcast's fault. Sometimes I have been driven to use my ancient AOL account which performs flawlessly, all the time.