[Dovecot] Dovecot mail-filter cannot work with large email about 700k

Hi All

I configured dovecot 2.1.7 with mail-filter plugin. It works well for small emails like server k big.(7k)

But it failed with larger emails about 700k.

The scripts hang out, and the mail-filter-out process does not exist and always in ps.

It does not work even I use "cat" in mail-filter-out.sh.

Where to set the size limit for mail-filter?

Do you know how to fix this? This bug also exists in 2.2.12.

Thanks!