Fatal error: mb_encode_mimeheader()

[typo]

Hello,
I have a problem with my sugar.
When i will send an email I become this line in my webbrowser

 Fatal error: Call to undefined function: mb_encode_mimeheader() in /srv/www/vhosts/domain/httpdocs/sugar/include/Localization/Localization.php on line 309 
  

I use version 4.50e

Can somebody help me with this problem?

[ruchida]

It seems that the php-mbstring extension is not enabled in your server, which is rquired to run 4.5.0. What is your server OS, PHP version? How did you install 4.5?