Delivery Error when Sender send long email message

For the past one month, We’ve been getting complains from customers saying that they are unable to send email to us. It happens to more than one email address (with different domain). I’ve checked there is no restriction being set as I’ve done internal telnet to my smtp server and send email using the customer email address and I can send internally. I’ve check my firewall also and there is no policy being set to block certain incoming emails.I found that if the emails contain long message, then my server will reject it.

I did a test as follow:

A = Yahoo email

B = Gmail email

C = Our Domino Email

All message is in plain texts with about 50kb. So it is a long message.

Scenario 1: A send to C – Result: A got failure notice saying “Remote host said: 554 Message rejected for policy reasons”

Scenario 1: B send to C – Result: A got failure notice saying “PERM_FAILURE: SMTP Error (state 16): 554 Message rejected for policy reasons.”

Scenario 1: A send to B – Result: B received A without any problem.

Questions:

How do I solve this problem? Is there a setting to set the message size.

PS: Email with attachment bigger than 1MB can go through. Only if the body of the message is long, then it’ll bounced back to the sender.

Subject: Delivery Error when Sender send long email message

Have you checked the message headers in the NDRs to make sure they are coming from your Domino server and not from some other box such as your firewall?

If so, do you have any Rules defined in your server configuration document? (Router/SMTP tab, Restrictions and Controls tab, Rules tab)

Subject: RE: Delivery Error when Sender send long email message

Yes. It is because of one of the rules. But the conditions of this rule doesn’t reflect to the emails being bounced back. Anyway, my problem is solved. Thanks much.