Problems Attaching Certain PNG Images

[amarand]

I've been using/administering Roundcube for awhile now, and I rarely have odd issues like this.  I'm using the latest (0.8.2) version on CentOS (6.3) with PHP 5.4.6.  I went to send a PNG file today, and it appeared to have attached, but after sending, it was not received, nor does the attachment show up in the message saved in the Sent folder.

I created a very small (20k) PNG and JPG file, and attached them both to separate e-mails with no problem. So clearly there's something with the original PNG file that's causing issues. The file itself is just a normal PNG file with transparency, which shouldn't be a problem, right?

I'm seeing no errors in the httpd logs for the server during the composition or transmission of the message.

I'm starting to use PNG more frequently now, and would like to resolve this before it becomes an issue.  ("I sent you the file" "I never got the file!" "Huh."  Then I call my memory into question and it's a big mess.)

Thoughts?

[SKaero]

Is there anything in the RoundCube error log?