Adjusting SMTP/milter timeout?

[millerdc]

Under ZCS 7.0.1 network I'm seeing an issue with 3rd party email clients smtp connections on slower networks and file attachments. There seems to be a timeout set to around two minutes on SMTP connections. I'm seeing the following error in the logs and on email clients when it takes over two minutes to send an email.


Mar 29 10:16:38 email postfix/cleanup[21031]: 6391C3536001: milter-reject: END-OF-MESSAGE from ip72-220-140-199.sd.sd.cox.net[72.220.140.199]: 4.7.1 Service unavailable - try again later; from=<millerdc@domain.com> to=<doej@domain.com> proto=ESMTP helo=<[192.168.0.100]>
Mar 29 10:16:38 email postfix/smtpd[18443]: disconnect from ip72-220-140-199.sd.sd.cox.net[72.220.140.199]

Now I have tested this on multiple speed connections and have ruled out that it is the size of attachment and email client. For example at home I get around 250K/sec to my work zimbra server. So I can send about a 15MB attachment with out getting the error. Anything longer goes past the timeout. From a faster net connection that gets about 2MB/sec I can send a 150MB attachment. What do I have to change to increase the timeout on smtp connections? Thanks.

[FritzBrause]

... same issue here with 7.0.1. If I check the possible values with

zmlocalconfig | grep -i milter

I get something like

milter_bind_port = 0
milter_in_process_mode = false
milter_max_idle_seconds = 120
milter_max_scheduled_write_bytes = 1048576
milter_max_sessions = 20000
milter_min_threads = 20
milter_thread_keep_alive_time = 60
milter_write_chunk_size = 1024
milter_write_timeout = 10

which seem to be the default values. I'll test if changing filter_write_timeout to a higher value will give better results. Otherwise I'll file a bug report.

[millerdc]

I have an open case with zimbra on this issue too. They say they are going to test this in their lab and get back to me. I have sent them the link to this thread since you are seeing the same thing.

[FritzBrause]

I dug a little deeper. Please feel free to pass this on to Zimbra:

It seems that this issue occurs with SMTP / STARTTLS and SSL connections only. If I switched the SMTP connection to plain SMTP using no encryption the error didn't occur. I'll verify this by some more testing.

The messages in the log file support this suspicion:

Apr  5 13:11:37 de-dd-srv-1101 postfix/cleanup[9091]: warning: milter inet:127.0.0.1:7026: can't read SMFIC_HEADER reply packet header: Success
Apr  5 13:11:37 de-dd-srv-1101 postfix/cleanup[9091]: 2F266C74E51: milter-reject: END-OF-MESSAGE from de-ch-srv-1102.office.managedhosting.de[213.23.10.202]: 4.7.1 Service unavailable - try again later; from=<noc@managedhosting.de> to=<noc@managedhosting.de> proto=ESMTP helo=<[192.168.160.3]>
Apr  5 13:11:42 de-dd-srv-1101 postfix/smtpd[9086]: disconnect from de-ch-srv-1102.office.managedhosting.de[213.23.10.202]

If you ask Google about "can't read SMFIC_HEADER reply packet header" there are a lot of answers pointing in our direction.

[ppaixao]

Hi all,

I've the same problem. Anyone knows how to solve?

Pedro Paixão

[FritzBrause]

... you may want to try if

zmlocalconfig -e milter_thread_keep_alive_time=120
zmlocalconfig -e milter_write_timeout=30
zmcontrol restart

will ease the pain a bit. Depending on your message size this might help already.

[millerdc]

Zimbra is still looking into the problem. I have been doing some tests myself. If I turn of the milter server I can send as large of an attachment as I want. We only allow authenticated and SSL encrypted connections to send mail. Turning it off is not an option for us. Well, neither is turning off milter since we use access control to distribution lists and milter server is required for it to work.

[rajeshkodali]

Hi,

I am also facing the same problem with milter. Went back to old postfix model of restricting users to mail to DL.

[gvillaran]

i have the same problem, and i use the milter for DL aswell, hope this gets fixed soon, my thunderbird and outlook users started to complain about this.

[gvillaran]

millerdc have you filled a bug report?

im trying to find it.