php - Codeigniter is not sending base_url in mail -

this first question, found here, time can't find anywhere.

i building project codeigniter 2.2, each time new user register welcome mail sent. problem mail sent if in message body url of website appears email not received, if there url email has no problem , received.

example 1 mail message: <h1><a href="'.site_url().'">welcome</a></h1> print debugger: message has been successfully… in email: nothing received…  example 2 mail message: <h1><a href="http://www.mywebsite.com">welcome</a></h1> print debugger: message has been successfully… in email: nothing received…  example 3 mail message: <h1><a href="http://www.google.com">welcome</a></h1> print debugger: message has been successfully… in email: mail received, welcome message google url  

if echo de site_url() on view, appears no problem. problem if want send via codeigniter email, or write , send it.

my server linux in godaddy. using sendmail gmail's smtp, i've tried servers, host, user , pass, yahoo, hotmail , website , same result, mail received when has url, url except mine.

it bug? please help