Sendmail error 421 4.4.1 collect: read timeout on connection from

tertius · 08-17-2006, 09:20 AM

Hi all,Please if someone can help me it would be greatly appriciated!!

I run FC5 for my mail server and standard mail server is sendmail 8.13.7. Now for about a weak now their is some problem and I have got no idea how to solve it.

It gives me this error :

SYSERR(root): collect: read timeout on connection from [mail server]
421 4.4.1 collect: read timeout on connection from [mail server]

Please can someone help me,I downgraded sendmail to version 8.13.5, mail went through for 20 min fine,then same message apears.. Strange thing is some mail goes through and only certain mails fail all the time.. Any suggestions??

wls · 08-26-2006, 12:44 AM

I also am seeing this with 8.3.17. But only with some (one?) site in particular. I'm scratching my head on this one.

blankbmx · 08-29-2006, 12:24 AM

when you send mail to the accounts that cannot recieve mail, do you get any bounceback messages? if so please post them here for review.

wls · 08-30-2006, 09:32 PM

I can do much better than a bounce message - I ran tcpdump -A on my firewall.

It appears that the final "." is placed after a tab and a space:

Code:

09:09:08.214105 IP [source IP].1700 > [my IP].smtp: P 111:117(6) ack 580 win 64956
E...".@.q..^&q.B.+...........N..P.......DATA^M

09:09:08.214622 IP [my IP].smtp
> [source IP].1700: P 580:630(50) ack 117 win 5840
E..Z..@.?..S.+..&q.B.....N......P....8..354 Enter mail, end with "." on a line b
y itself^M

(text follows followed by a final):
^M

        .^M   <-- Note this is a /t/s.

09:09:08.314569 IP [my IP].smtp
> [source IP].1700: . ack 117 win 5840 <nop,nop,sack sack 1 {1577:3
416} >
E..4..@.?..w.+..&q.B.....N.:...............

        ...Z....
09:13:08.247173 IP [my IP].smtp
> [source IP]1387: P 630:741(111) ack 117 win 5840 <nop,nop,sack s
ack 1 {1577:3416} >
E...U.@.?....+..&q.B...k.".................

        ...8...g421 4.4.1 collect: read timeout on connection from [source IP], from=<user@[source IP's MX]>^M

Now I presume what may be happening is that because the DATA terminator is not a "pure" "." sendmail never recognizes the end-of-data... and thus times out. Plausible?

SteveK1979 · 03-18-2007, 05:51 AM

Hi,

Old thread, I know, but did you ever get to the bottom of this problem?

Cheers,
Steve

wls · 03-19-2007, 06:12 PM

I did not solve this - rather, the sending mailer had a misconfiguration problem which they eventually fixed (and the problem with the /t before the .^M went away). I'm not sure how other MTAs (e.g. Exchange) would have handled that syntax error. I'd also be curious as to what mailer they were using that could have caused their problem.

rene-w · 06-04-2007, 09:01 AM

Quote:

Originally Posted by wls

I did not solve this - rather, the sending mailer had a misconfiguration problem which they eventually fixed (and the problem with the /t before the .^M went away). I'm not sure how other MTAs (e.g. Exchange) would have handled that syntax error. I'd also be curious as to what mailer they were using that could have caused their problem.

I found this topic because I am sitting on the other end of the line - having the problem as the sender of the e-mail.

In my SMTP Log every connection ends at 354+Enter+mail,+end+with+"."+on+a+line+by+itself.

I just got the log-file of the recipient which says:
SYSERR(root): collect: read timeout on connection from mymailserver.at

We had a few mail sending issues (everytime with the connection dropped after the 354 ... was received) because of bad formatted newlines (\n was used but \r\n is expected) - but these problems are solved.

Our system generates about 500 Messages every day and sends them to about 400-500 different receipients, but just one of those receipients generates this error and the mail cannot be sent. (the product of my company are pdf files which are delivered by email...)

Opening the undelivered Mail with the regular e-mail program and resending it over the normal MTA (Exchange

) is working fine.
So it has to do with the formatting, newlines, ... of the message content.

If someone has a clue what the problem could be please reply.

thank you in advance, yours rene

yatming · 07-12-2007, 05:54 AM

Hi All,

My smtp server also encounter the same problem. Some of my customers using the same ISP services which has read timeout issues. When sending relatively large emails (several MB, usually in ZIP format) from that ISP, the connection will be idle for TCP timeout and then report:

SYSERR(root): collect: read timeout on connection from SERVER.NAME, from=<some@email>

My server is running FC6 and sendmail 8.13.8
I had sent complaint to the sender ISP, but they reply "no problem". I really wonder what mail server they are using.

What can I do is to ask my customer to use our server's web mail service to send email to their colleagues. But they still have problem for their customers sending email from that ISP.

Any suggested work around or fixing?

Iggy · 08-08-2007, 09:41 AM

I had this message on newly installed FreeBSD machine with Sendmail 8.13.8 and fixed it in the following way: if system doesnt get SYN on slow or bad connection (such as SMTP)- it disconnects due to timeout. I increase the sysctl net.inet.tcp.keepinit default value of 75000 ms to 120000, and now have no annoying "read timeout on connection..." message.

moymexico · 10-10-2007, 10:14 AM

Hi,

Quote:

I increase the sysctl net.inet.tcp.keepinit default value of 75000 ms to 120000, and now have no annoying "read timeout on connection..." message.

Iggy, where do you make such increase... or I should say how do you make such increase... as you can see I am not very skilled

. I have RHEL3 and sendmail.

Thanks

rajronju · 01-31-2010, 04:18 AM

I also faced this problem. But after limiting the mail size to 5 MB I overcome it. As you know mail exchangers create session for 5 minutes(i don't know details). So in this 5 minutes period if your total mail not transferred it will reply connection timed out. It also true for low grade connectivity.

winjon · 09-12-2010, 08:37 PM

This is the old post by I'm having the same problem of
451 4.4.1 reply: read error
timeout waiting for input from ... during client greeting

My sendmail sends out emails to over 50,000 emails.
Searchinng through maillog I found the errors are from differnt Exim 4.69 receiving servers.

i believe the problem is on my end. Help please..