"Chunk exceeds message size limit"

[Thorben Thuermer]

Hello,

i am running postfix 3.4.1-1 (from debian sid).

i recently noticed that mails from multiple senders (most importantly google 
mail)
are being rejected with:
>  552 5.3.4 Chunk exceeds message size limit

postfix logs:
> Mar 19 17:42:48 ngs postfix/smtpd[22671]: warning: 25E74C1: BDAT request from 
> mail-ed1-f44.google.com[209.85.208.44] exceeds message size limit

this happens regardless of the actual message size,
even a one-line plaintext message is rejected.

/etc/postfix/main.cf has:
header_size_limit = 4096000
message_size_limit = 0

downgrading to 3.3.2 fixed the issue.

i found the responsible code in postfix-3.4.1/src/smtpd/smtpd.c 
commenting out that check also fixes the issue.

    /* Block too large chunks. */
    if (state->act_size > var_message_limit - chunk_size) {
        state->error_mask |= MAIL_ERROR_POLICY;
        msg_warn("%s: BDAT request from %s exceeds message size limit",
                 state->queue_id ? state->queue_id : "NOQUEUE",
                 state->namaddr);
        return skip_bdat(state, chunk_size, final_chunk,
                         "552 5.3.4 Chunk exceeds message size limit");
    }

- T.