Internet FAQs

Why would an email I try to send be undeliverable?

Check the spelling of the username and domain in the destination email address. Many servers on the Internet are UNIX-based servers which are case sensitive. On these servers,, for example, is not the same as or

It is also possible that your recipient has a “full mailbox,” which means their provider’s system has reached its mail storage limit. You can also verify if the recipient has blocked your email address or domain.