can't send large mail to yahoo

[dalmate]

After tracking zimbra's logs, I see that zimbra can't send large mail to yahoo (lager than 4MB). In the zimbra.log, it said:

...lost connection with ..... while sending end of data -- message may be sent more than one

But the emails has a size smaller than 4MB can be sent properly to yahoo, not have any problems.
Have any one solution? or this is a bug of postfix?

[ewilen]

I've been seeing this, too. I assume it's because of Yahoo, not Zimbra.

Edit: have you tried sending to Yahoo by other means, e.g. Gmail, or a q&d install of some other MTA?

[dalmate]

Originally Posted by ewilen

I've been seeing this, too. I assume it's because of Yahoo, not Zimbra.

Edit: have you tried sending to Yahoo by other means, e.g. Gmail, or a q&d install of some other MTA?

Yes, I tried to send to yahoo by an other mail service such as: gmail, hotmail,...
with the same mail, same large. It's succefull.
I also sent the same mail, same large from my server (using zimbra) to gmail and hotmail, too. It's succefull.
I've read in some forums, they said that it's because of yahoo. But someone said that it's maybe because of the timeout of the postfix. But I can't modify the connection timeout of postfix in zimbra.

[ewilen]

Maybe this will help: Postfix Frequently Asked Questions

To test, I would set a smaller MTU on your server. You'll have to look up how to do that with Ubuntu.

How small? I don't know. If you have the luxury of not having users to worry about, I'd set it to 1400, then test, and if that didn't work, I'd cut it in half to 700, and so on. (Although, 700 is really low.) EDIT: Or maybe better, disable path MTU discovery as recommended at Postfix 0112: Re: timeout after DATA. (See also PMTU - Path MTU Discovery.)

If you find a value that works, then I'd suspect an issue with IP path MTU discovery as described in the FAQ. At that point you'd have a choice: either try to find the ideal MTU to allow sending large files to Yahoo, or examine whatever firewalls/routers are under your control that might be dropping ICMP feedback messages.

I hope this helps. Please let us know if you come up with anything.

As for setting the timeout, you probably can set smtp_data_done_timeout in zmmta.cf, but it's not the first avenue I'd pursue.

[rafael.alvarez]

Hi Eliot

We are having the same problem only when sending big mails to yahoo.com accounts. Recently migrated from GroupWise to Zimbra 6.0.6.

Our system is behind a NAT router. We will try to reduce the MTU at the router and share with you if solved.

Thanks for the info

[ewilen]

Hi, Rafael. I just want to note that now I kind of doubt this has anything to do with IP path MTU discovery. Based on some test emails I sent a while back, I'll bet it's just Yahoo throttling acceptance of multiple large emails from the same host. On the other hand, since you're suggesting this issue only arose after a switch from Groupwise...I don't really know.

I'll be interested to see if your tests reveal anything.

[rafael.alvarez]

Hi Elliot:

Sure. I will let you know by tomorrow (by time difference) cause we are in Spain.

I also disabled path MTU at the Ubuntu Server.

[rafael.alvarez]

Hi Eliot:

Sorry to say that. Disabling path_mtu_discovery did not fixed the problem.
I had tried also disabling antivirus or antispam with the same result.

Thanks anyways

[alherman]

Hi All,

i have same problem to, can not send to yahoo more than 1mb.

send to gmail, mail, other domain can dan more than 1mb ok. in yahoo said sometime "broken pipe" & sometime said "451 4.4.1 reply: read error from a.mx.mail.yahoo.com

i do not know why this happen? any body have clue?

br,
al

[rafael.alvarez]

Hi Al:

We have found lot of problems at the internet with yahoo. In our case we can send small mails with attachments less than 4 mb.

With large attachments we receive a different message than yours:

lost connection with mx1.mail.eu.yahoo.com[77.238.177.9] while sending end of data -- message may be sent more than once

and the message goes to the deferred queue.

We have found this information (sorry in spanish but I think you could understand) for postfix user with the same problem (solved for him) that did not worked in our case since we do not have checksum errors. Maybe can help in your case.

Networking Tips: Problemas con Postfix dsn= 4.4.2

Best Regards