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Questions tagged [smtp]

SMTP is the Simple Mail Transfer Protocol, the most recent standard of which is defined in RFC 5321. It's the Internet standard for sending and receiving email.

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POSTFIX cant connect from SMTP with TLS

Thanks all for helping me :),i was working a direct bulk mail sender project, my program was running properly then it gave me an error then i've spend too much time with a lot of searching from ...
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1answer
8 views

Setting Postfix for outbound email via SMTP with local root delivery for cron reports

I recently had to diagnose a couple of servers running Postfix which emailed results of rsync cronjobs when they returned a non-OK value. While Postfix was emailing the recipients on rsync failure, I ...
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55 views

SMTP Problems due to CN vs SNI on the Certificate?

I have a scenario where I'm using a shared mail server (cPanel) for SMTP on multiple domains for several clients. I hit an issue where Ruby's OpenSSL library complains that the hostname "smtp.domain2....
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23 views

How does yum-cron send emails from localhost?

I have an amazon linux 2 server running in the aws cloud and I have yum-cron running on it. I have an email domain mydomain.com which is running on a separate server in a completely different cloud ...
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PTR doesn't match hostname on SMTP HELO command. What to do?

I'm struggling with an issue regarding hosts connecting to my SMTP server. For instance, one client is connecting to my SMTP server with the given hostname : EUR02-AM5-obe.outbound.protection.outlook....
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45 views

Do any reputable mail servers require STARTTLS encryption for SMTP delivery?

Are there any large, reputable MTAs (like gmail, hotmail, icloud, etc) that will bounce mail or otherwise fail to deliver if the receiving MTA doesn't support STARTTLS? Put another way, will ...
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1answer
19 views

Postfix local delivery causes recipients to not show

I'm quite new to posting, please help me if I'm in the wrong place. I have a debian email server, which is working for outgoing and incoming with external SMTP service. postfix, dovecot, mariadb, ...
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IIS 7 SMTP not relaying one specific domain

We have an old 2008R2 Server with IIS running a SMTP process that is set to relay internal emails to an exchange server (external go out). We have 12 domains setup and all work well apart from one ...
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Whitelist outgoing SMTP server using CSF

Am trying to setup Mandrill for transactional emails for one of my web application. I decided to use the SMTP method(credentials from Mandrill) than using API as it would be easy for me. In my VPS ...
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0answers
35 views

Connecting to a external exchange server via linux/php?

We have an SMTP relay available that we are using on windows servers. [mail function] ; For Win32 only. ; http://php.net/smtp SMTP = email.relay.url ; http://php.net/smtp-port smtp_port = 25 ...
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58 views

Server responded: 503 AUTH command used when not advertised\r\n?

I recently migrated from one server where my mail settings worked without a problem to a new server which now results in the following error: Server responded: 503 AUTH command used when not ...
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27 views

Can SPF record include multiple A domains

Hello would this be a valid SPF record for domain1.com using a records from different domains? v=spf1 a:mail.domain2.com a:mail.domain3.com -all This question is similar but uses the include and not ...
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1answer
22 views

How outbound SMTP gets encrypted by the client?

When my SMTP server sends an email to another server and is supposed to use TLS, the receiver will offer his destination domain certificate (I assume). Which certificate does my server use to encrypt ...
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1answer
48 views

SMTP Open Relay using AWS SES

Good day, As an ISP, We currently have an open SMTP relay that we allow access from our customer's IP ranges. This is a very low volume email platform. We are considering to move this service to the ...
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1answer
33 views

Exim Find Total Number Of Emails Sent Within Last 24 Hours On Per User Basis

Want to go through exim logs for past 24 hours and sum up total number of emails on per user basis, please suggest me command(s) I know how to view emails currently in queue.. but I want to find ...
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1answer
47 views

Open Port 25 for Message Receipt Only in Postfix

I have configured Postfix as an SMTP server, running on a non-standard port, using TLS, with relay. However, I want to add the ability to receive mail directly to the user accounts on the system, and ...
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1answer
60 views

Is Office 365 Exchange capable of SMTP connection-stage rejection?

Microsoft Office 365 Top senders and recipients report shows that 15-20 % of messages in the tenant are from postmaster@example.com i.e. Office 365 Exchange sends a lot of Non-Delivery Notifications (...
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Configure postfix to send emails per domain from each virtual server

In my setup I have installed virtualmin for virtual servers. I have following virtual servers with their own dedicated ip address. Postfix is configured as per this method to use dedicated ip for each ...
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1answer
63 views

Exim4 : “Connection timed out” whatever the forwarding smtp server

Exim is configured on a newly provisioned VM from a public cloud provider with public IPs (scaleway.net) Purpose: Be able to send mails from CLI (or scripts) to public destination recipients (gmail,...
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1answer
122 views

Postfix: How to limit outgoing messages (smtp) while sender_dependent_default_transport_maps is enabled?

I would appreciate and thankful if anybody could suggest me regarding the following issue I am dealing with for the last 7 days. Current Condition: 1 working mail server (collocation) that host for ...
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2answers
67 views

Is a mail subdomain necessary?

I have just taken ownership of a domain which had a couple of associated email addresses. I have left the mail boxes with the previous host, and so have been looking at updating the MX records in my ...
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1answer
37 views

SMTP MTA to MTA authentication

I still have trouble understanding how a receiving MTA authenticates the forwarding MTA. I imagine an email that is forwarded by domain A's MTAA to domain B's MTAB. Steps to take by MTAA: Find MX ...
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1answer
111 views

Postfix 'too many errors' after many RSET commands

I have a client who is complaining that their invoice emails are not all being sent out correctly. As far as I'm aware their invoicing software is designed to send emails directly. Looking at a ...
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1answer
39 views

Postfix bounce when unable to validate TLS option

I'm using postfix as mail transfer agent on my mailgateway to send and receive emails. Because I'm communicating with sensitive information I'm using the tls options to validate the receivers mx. He ...
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0answers
48 views

Server 2012 R2 SMTP service not sending mail to non TLS servers

We have SMTP virtual server on server 2012 R2 server. I have configured it to use TLS connection. We do have real sertificate etc. Everything works fine except mail that is going to mail server which ...
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2answers
88 views

One domain with multiple MX servers and forwarding instead of erroring

I have a domain with few hundred email addresses. We are migrating our hosting to multiple ISPConfig servers. My problem is if someone sends email to email@domain.example and if the email does not ...
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1answer
32 views

Postfix is appending myorigin to non-FQDNs despite “append_at_myorigin = no”

I have postfix and a local LMTP server running. In my main.cf, I have append_at_myorigin = no. When I run postconf|grep append_at_myorigin I get that this value is no. But for some reason, postfix is ...
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1answer
28 views

Some users seeing unformatted emails with winmail.dat files while others aren't

We have a hosted BitBucket instance that is sending emails via SMTP through Exchange 365 to external users. Some of those users are seeing the properly formatted emails when looking at them in Gmail. ...
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1answer
64 views

Problems with certificate in Exchange 2016

We have just installed a new mailserver, with exchange 2016. We need to have our wildcard certificate assigned with the smtp service in exchange. I edit the certificate in exhange EAC, tick the ...
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2answers
42 views

Multiple SPF entries in same or separate TXT records

I want to use a mass mailing service, e.g. sendgrid, mailgun, etc. And so I must update my zone file to include the correct SPF records. Suppose my domain is example.com. My DNS provider ...
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1answer
170 views

Postfix 451, 4.3.0 : Temporary lookup failure

we've followed the guide HERE to configure a Postfix. After sending a message via telnet we receive the following error: Oct 8 18:52:01 mail postfix/smtpd[3719]: connect from unknown[10.10.10.9] Oct ...
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0answers
27 views

Postfix header_checks in psql

In Postfix is it at all possible to perform header checks based on a PSQL lookup? I haven't found anything explicitly saying you can...but also haven't found anything supporting it. Ideally, I want ...
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0answers
35 views

Do you need to use IMAP to read bounced emails?

I'm writing a send email app in Laravel which will use my own email servers. Many apps read an IMAP inbox to log the number of bounces a user might receive- using some cron to check and delete bounces ...
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1answer
80 views

Why smtp server can not be telnet?

https://www.webdigi.co.uk/blog/2009/how-to-check-if-an-email-address-exists-without-sending-an-email/ I am following the above instruction to telnet an email server of gmail. But I got an error. ...
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1answer
37 views

iptables block outgoing on port, allow selected IP's [duplicate]

Debian 7 iptables v1.4.14 (there are no rules) Need to block all outgoing connections on ports 25,587,465 and allow only on specific IP's. What I've tried: iptables -A OUTPUT -p tcp --match ...
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0answers
59 views

Is there an option for nginx mail module to use STARTTLS on upstream servers?

I'm currently setting up a mail cluster for sending mails. To avoid sending limits of various providers (like gmx) I decided to setup a smtp loadbalancer using nginx and multiple postfix servers as ...
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0answers
43 views

Where does sendmail get its user authentication information?

I set up a new remote CentOS email server using sendmail and dovecot. I am able to receive mail into mailboxes but can not use SMTP to send. Trying to login by hand using # telnet mail.steelydev....
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0answers
16 views

Why is my firewall rule being ignored?

I'm having difficulty getting the firewall on a Draytek Vigor 3220 to pass incoming connections to port 25. I've set a rule to pass TCP packets from WAN to LAN from any source IP address and port to ...
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1answer
51 views

iredmail - Emails go out but don't come in

I setup an iredmail server so that my website can send registration emails and all that sort of thing. Problem is, it can send mail just fine (And even inbox) but it can't receive. Port 25 is open, ...
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2answers
2k views

554+5.2.0+STOREDRV.Submission.Exception:SendAsDeniedException in IIS SMTP Relay When Scanning to Email from a Sharp MX-M364N

I am getting the following error in my Windows Server 2012 R2 - IIS6 - SMTP Relay logs when I send a scan from a Sharp MX-M364N copier: 2018-09-25 20:28:54 40.97.132.2 OutboundConnectionResponse ...
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1answer
42 views

Postfix can't send or recieve emails

I have setup PostFix that is also running with dovecot on my server. My server is running Ubuntu 16.04. I cannot send or receive emails from squirrelmail that is also running on my server and it ...
0
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1answer
100 views

Postfix auth issue

I'm currently facing auth issue. When I'm trying to auth via telnet, I face an issue "535 5.7.8 Error: authentication failed: authentication failure" I use password and login the same, as I use for ...
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1answer
129 views

EXIM SMTP allows to send mails without login / authentication via telnet to any domain

I'm ashamed, but I have to ask for help. My server is being used for sending spam, I've found out I can simply connect with telnet (edit: from any server in office, home and even directly from CMD/...
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1answer
41 views

Does email from IIS SMTP get rejected?

A client has been using IIS v6 SMTP over Windows 2008 R2 for many years to send out automated server notifications. Their apps use Blat to send through localhost with no authentication. Email seems to ...
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1answer
57 views

How to send encrypted message using postfix?

I have some application on ubuntu 18.4 vps. i can send mails using postfix but gmail says it is not encrypted. postfix config file is: # See /usr/share/postfix/main.cf.dist for a commented, more ...
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2answers
324 views

iDRAC 9 Enterprise SMTP alerts w/Office 365

I'm running a Dell PowerEdge T440 with iDRAC9 Enterprise. I'm attempting to setup SMTP alerts using Office 365. I have been unable to successfully send a test e-mail at all. I receive the error: ...
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0answers
20 views

Insert several servers IP via txt/csv under SMTP on IIS 6 (Windows Server 2012) via shell/vbscript/anything [duplicate]

We would like to import several servers authorized IP's to send mails to the relay field on IIS 6 (WS2012). Do anyone have a viable way to do it? Many scripts were tested, none successfully.
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1answer
75 views

Unable to block port 25 on server

When I scan my server using nmap $ sudo nmap -sS IP.ADDR.OF.SRVR, I see a line with 25/tcp open smtp. This is despite the fact that I'm not running postfix, exim or any other kind of mail server ...
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1answer
160 views

Mailgun/Postfix: Relaying Denied

I have checked the other threads on here and none seem to resolve my issue. I am trying to relay my outgoing emails from Postfix to Mailgun via SMTP. My server is also running Plesk. My Postfix ...
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0answers
20 views

Multiple Received headers with sendmail php

I just initialized sendmail and I'm sending some test mails to my personal email address with a very simple PHP script. I noticed something odd, here: Received: from mydomain (MYIP.ip98.myhostname [...