Mailbox unavailable

The typical error report for the "Mailbox unavailable" error looks like this:

Delivering via
< 220 ESMTP Welcome to Road Runner. NO UCE *** FOR AUTHORIZED USE ONLY! ***
< 250 Hello [], pleased to meet you
< 550 5.7.1 Mail Refused - - See

The explanation of the failure to deliver the message is in the last string (please follow the url above). The mail has been rejected because the mail server does not accept mail from dynamic IP addresses. To bypass this restriction, you should send mail to these addresses via your ISP's SMTP server. Please open the Settings/ISP Troubleshooting menu in Atomic Mail Sender and specify the mail server address there (see the screenshot below). It should help.

(Usually, you should not select "ESMTP Authentication" and "POP before SMTP". It is required only if your ISP requests authentication before sending mail.)

Fixing 'Mailbox unavailable' errors


See also other error types:

How to get the full version of Atomic Mail Sender

To order Atomic Mail Sender, simply click the link below or go to this section to learn more about alternative payment methods. Also, before ordering, you can get the downloadable version of the program here.