Allowed memory size of xxx bytes exhausted

I'm sending e-mails with images and text to my users, every time other images. I'm doing it by loop every time creating object, images etc

while(..)
{
$message_object = new email_message_class;

# adding something about 10 images
$message_object->CreateFilePart($obraz,$pipd);
#... etc

$message_object->Send();
}

But after sending something about 100, sometimes 150 mails I have memory trouble

PHP Fatal error: Allowed memory size of 134217728 bytes exhausted

Every message have something about 30KB. I don't cache images, CreateFileImage parameter table looks like

$obraz['FileName']="/home/www/image.gif";
$obraz['Content-Type']='automatic/name';
$obraz['Name']='image.gif';
$obraz['Disposition']='inline';
#$obraz['Cache']=1;

I tried

$message_object->Send();
unset($message_object);

but have the same effect.

So probably CreateFileImage function is making cache of the image files no mather of $obraz['Cache']=1 parameter, I didn't found any function to destruct it permamently.

Have you any suggestion?

If the message is different for every user, you should call the ResetMessage() function before composing the message for each new user.

I've seen this function but for example what if I have 2 objects with different messages?
ResetMessage() don't get any arguments so which of the object will be reseted? First of the declared? Second? Both?

That is a function to call on a given object. So it only resets the definition of the last message that it sent. Other objects are not affected.