Note: It's never a good idea to post your actual email address on a public forum , (unless the address you posted was fake and just an example) as there are "bots" buzzing around trying to scavenge up these addresses for spam. But that point is moot now. I'd keep it in mind for the future.
Ok, the possible fix with explanation (copied/pasted from another website):
Port: 25, Secure(SSL): No, Server Error: 530, Error Number: 0x800CCC78
Now you are reaching the Outgoing SMTP Mail Server, but it won't process your request without further authorization.
<b>You will need to go into your Email Software and find the setting that indicates that your Outgoing SMTP requires further authorization. Select this setting and enter the username and password required by your ISP (or reqired by who ever is the administrator of the Outgoing SMTP Mail Server that's not blocked by your ISP).</b>
I'm sure this has been answered many times before-but I cannot find it. Sure would appreciate help on how to correct whatever causes the following error message. I have tried all I can think of plus web searches.
The message could not be sent because the server rejected the sender's e-mail address. The sender's e-mail address was 'firstname.lastname@example.org'. Subject 'Batman!', Account: 'pop.suddenlink.net', Server: 'smtp.suddenlink.net', Protocol: SMTP, Server Response: '553 Authentication is required to send mail as <email@example.com>', Port: 25, Secure(SSL): No, Server Error: 553, Error Number: 0x800CCC78