Sendmail: Increase header size?

I am not sending an email with a huge header to anyone, or at least I don't think so, but I may not understand the workings of Sendmail properly.

The only place where there is a huge header is when my PERL applications gives the email to Sendmail with around 2,000 members in the Bcc: field. After that, each recipient gets a short header that only contains his or her email address under Bcc.

So the error message is coming directly back to me from Sendmail before a single email has been sent out. At least, that's my understanding.

What exactly does 'O MaxHeadersLength=262154' in sendmail.cf do? No matter what I set it to, I get back the message from Sendmail:
'Headers too large (32768 max) '
even when I have set MaxHeadersLength=262154

Thanks for your suggestion, but still confused,
Al

Seems this is a tough one.

I changed every .CF file in /etc/mail including sendmail.cf, freebsd.cf and freebsd.submit.cf to make
o MaxHeadersLength=262154

Between each modification, I did a 'Make Stop' and a 'Make Start' as well as a 'restart_apache'. When I tried to send a message with 2,000 email addresses in the Bcc fiels, I still got the same error message:
Headers too large (32768 max)

I tried adding '-c /etc/mail/sendmail.cf' when calling sendmail to force it to use a particular .CF file, but I just got a bunch of errors complaining about file permissions.

Any Sendmail gurus out there?

Al

There is sendmail TA for that

I wonder why you post all bcc headers for MTA to clear them???

What's a TA?

I'm not sure I understand your second question, but I basically pass (from a PERL script) an email to Senndmail. It contains a Bcc list of around 2,000 member addresses and it sends them all out. It works perfectly when I only have, say, 1,000 addresses, but I get the 'Headers too large (32768 max)' message when I have more Bcc addresses than that.

Al

TA is Topic Area....
You have to alter perl script.
Bcc: attribute of message does not alter its delivery path.

Alter the Perl script in what way?

The large Bcc list of 2,000 addresses pushes the total headers length over 32768, hence the error from Sendmail. A shorter Bcc list (1,000 addresses) works perfectly.

So doesn't this tell me that my Perl script is working perfectly?

By the way, do you know where the Sendmail TA is? I can't find it.

Thanks,
Al

Adding Bcc: filed in mail message does not contribute to its delivery.

Sorry, I simply do not understand how your suggestion relates to my problem.

Once again there is NO problem with delivery. The messages get delivered perfectly if there are only around 1,200 addresses in the Bcc field. However, when theree are 2,000 messages in the Bcc field, then I get the error message from Sendmail:  'Headers too large (32768 max)'

Al

You can reduce message size by omitting all Bcc: addresses from header.

(from memory)  It is RFC 822 that limits the header to 32K not sendmail. (or any other MTA)

To extend what gheist is saying, you must do it programatically... Send them in 3 batches of 1000. Easy Done.

Okay, it's looking like I have to modify the Perl code to send in batches (something I was hoping to avoid, but I'll do it).

However, I still have to ask what 'MaxHeadersLength' in Sendmail.cf is for?

Al

It's been several years since I used sendmail but as I recall you can sent an even tighter limit than the RFC requires. (up to the hard 32K limit) Like most things in sendmail, it's there for the one person in the history of mankind who needed it.

Actually is is not that bad, ISP's use(d) it to limit people from spamming. Advancements in spamming technology make it look quaint by today's standards.

Thanks to gheist and Bienville for pointing me in the right direction. You convinced me that there is no way to make Sendmail accept a total headers length greater than 32,768 no matter what value I set MaxHeadersLength to. As you suggested, MaxHeadersLength may be less than 32,768, but not greater.

So I went back to my Perl code and added a "Batch Size" parameter (500 by default). Now the Perl script sends the Bcc list in batches of 500 and it works like a charm.

Question: How do I split the 500 points between Bienville and gheist?

Al

Easy, give them all to him. (really)