"avatar" and "osticket" directories on the same level.

File format avatars: IOFamily@gmail.com.jpg the same as the address in the profile + JPG.
The width of the avatars - 80px (96px).

Find and edit file - osticket/upload/include/class.avatar.php

Make changes to it as shown below.

Code part:

abstract class Avatar {
    var $user;

function __construct($user) {
    $this->user = $user;
    $this->email = $user->getEmail();
}

abstract function getUrl($size);

function LoadLocal($size) {
    $eml = $this->email; // from construct abstract class Avatar
    $im = '../../../avatar/'.$eml.'.jpg';
    if(!is_readable($im)){ return $this->getUrl($size);    }
    return $im;
}

function getImageTag($size=null) {
    $img = $this->LoadLocal($size);
    $style = ($size)
        ? sprintf('style="max-height:%spx"', $size)
        : '';
    return "<img {$style} class=\"avatar\" alt=\""
        .__('Avatar').'" src="'.$img.'" />';
}

function __toString() {
    return $this->getImageTag();
}

function isChangeable() {
    return false;
}
function toggle() {}

}