If you let us know some more details maybe we can help. What version of Android are you running? Are you using the default email app or a third-party app? Which mail service do use? Has this been a long time problem or did it just start happening recently? All these things are relevant to your query.
There are many reasons for this kind of error. The most obvious would be typing the server name incorrectly or assigning the wrong port. You could also simply have lost your data connection or the server might be offline. As @svim states, more information would be helpful.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.