URGENT: Cannot send emails

[ccanei]

Hi Folks,

I am using Sentora 1.0.3 in a CentOS 6.7 (Final) for 3 months and now something is wrong.
I have no idea about what happened, but yesterday I was using my VPS without problems, and today I cannot send emails, but I m receiving emails normally (I believe).

Also, I did some test, for example MXToolBox, and no problem reported, I am not blacklist, postfix is sending (I sent a test email from postfix to my sentora email) but emails are not sent. It is very strange, because I didn't receive any error message (return error message) and email are not sent. I sent emails to my personal emails: @outlook.com; @yahoo.com; @bol.com.br; and @gmail.com and I didn't receive emails sent from my VPS.

Currently I can send emails only inside my VPS, I have few domains there and I can send and receive emails, but nothing outside my VPS. My domain is: virtualizeja.com.br

Port 25 & 587 is open, and I didn't change my Sentora/VPS. No idea about that happens.

Can someone help me?

[Me.B]

Did you check if your IP is not blacklisted? OR ISP not blocking your smtp?

M B

[ccanei]

hey man... yep, my IP's are not blacklisted, and no reason to my ISP block my SMTP. Anyway, how can I check?

I use mxtoolbox to verify:

http://mxtoolbox.com/domain/carvalhovilela.com.br/
http://mxtoolbox.com/domain/virtualizeja.com.br/
http://mxtoolbox.com/SuperTool.aspx?acti...tworktools
http://mxtoolbox.com/SuperTool.aspx?acti...tworktools#

And IP reputation check:

Cyren IP Query Result:
IP Address:23.89.158.171
Risk Level:No Risk
Description:This IP address has not been used for sending Spam

Really, I didn't change settings or any information, and today it isn't working

[Me.B]

Ports seem responding.

What did you change? Could you check logs if you ever got those emails?

Any antispam there? TLS? Greylisting?

[ccanei]

I didn't change. I didn't update.
Yesterday it was working fine, and today not. No reason and no idea to fix

I checked maillog 1 hour ago and I saw last emails that I received.

I am reading information to install SpamAssassin, but I didn't yet. No TLS, no Greylist.

[Me.B]

Check logs.

Try telnet to simulate email sending.

M B

[ccanei]

Currently I am using http://checktls.com to test.

Here is the log:

Checking contato@virtualizeja.com.br
looking up MX hosts on domain "virtualizeja.com.br"

    mail.virtualizeja.com.br (preference:10)

Trying TLS on mail.virtualizeja.com.br[23.89.158.171] (10):
seconds         test stage and result
[000.211]         Connected to server
[000.394]     <--     220 painel.virtualizeja.com.br ESMTP
[000.394]         We are allowed to connect
[000.395]     -->     EHLO checktls.com
[000.457]     <--     250-painel.virtualizeja.com.br
250-PIPELINING
250-SIZE 20480000
250-ETRN
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
[000.457]         We can use this server
[000.457]         TLS is not an option on this server
[000.457]     -->     MAIL FROM:<test@checktls.com>
[000.517]     <--     250 2.1.0 Ok
[000.518]         Sender is OK
[000.518]     -->     RCPT TO:<contato@virtualizeja.com.br>
[000.583]     <--     250 2.1.5 Ok
[000.583]         Recipient OK, E-mail address proofed
[000.583]     -->     QUIT
[000.643]     <--     221 2.0.0 Bye

And a simple telnet connection to ports 25, 465 and 587 are OK, connection allowed, no blocks.

[ccanei]

Just to Update

I am talking with my ISP and probability it is a ISP block.
When I finish the call I will update here.

[ccanei]

Sorry, it wasn't a ISP block.
Now I am receiving some error messages, like this one:
----------------------
From: Mail Delivery System [mailto:MAILER-DAEMON@webmail.virtualizeja.com.br]
Sent: Wednesday, 6 de julho de 2016 14:56
To: dulcevilela@carvalhovilela.com.br
Subject: Delayed Mail (still being retried)

This is the mail system at host painel.virtualizeja.com.br.
#################################################################### THIS IS A WARNING ONLY. YOU DO NOT NEED TO RESEND YOUR MESSAGE. #
###################################################################

Your message could not be delivered for more than 4 hour(s).
It will be retried until it is 5 day(s) old.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can delete your own
text from the attached returned message.

The mail system
<d.helena.vilela@bol.com.br>: connect to mx3.bol.com.br[200.147.36.13]:25:
Connection refused
------------------------------
Now my question is: Why am I receiving 'Connection refused' error message?

[ccanei]

Just one more update.

I have no idea the cause of this problem, but after I delete all emails in deferred queue ([root@ ~]

#qshape

deferred = to see emails in deferred queue) and restarted server, emails are working again.

I am checking to try to identify the real cause of that, but no news at now.