Do anyone help me? (Phpmailer questions)

[catpoint]

I upgraded Phpmailer to 2.5 coz i changed my php version to 5.2.10

but i found a very strange issue: Once i tried to send email with images attachments or embedding pictures, i cannot receive it. later, i found i can receive small gif file less than 2K

but it works well with other file types, such as doc,pdf etc. no matter how big the file size is

 

in the beginning, i think there's something wrong with my mail server, but i can send picture by outlook.

 

so, what on earth ...????

thanks very much!