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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Rewriting message header To: field when sending email
I am configuring an SMTP server with Postfix (v3.7.3) for local (i.e. host only) mail sending on openSUSE 15.5 Leap.
What I would like is to send messages to local "users" (there is no real ...
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stunnel smtp tls frontend server/proxy for remote backend postfix
I'm running stunnel in server mode and listening on port 587 and trying to connect to a remote postfix server running on port 25.
NB: the two servers are connected via zerortier, which may or may not ...
google-cloud-platform
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Can I Force Implicit TLS Connection For Port 587 On Postfix?
I have read many articles saying port 587 by default is explicit TLS. This means it's STARTTLS. It asks the server on an unsecured connection if TLS is supported and if it is, it continues with an ...
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Wrap plain text mail in html
we use Postfix as MTA to send our mails from our system. Unfortunately we have an old persistent system which we cannot change, which sends mails to our customers in plain text format. I would like to ...
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Exchange Online ESMTP responds differently from different clients - Windows 10 vs Windows Server 2019
When I telnet to our Exchange Online's SMTP server address (****.mail.protection.outlook.com, port 25) I get two different responses or types of connect depending on what machine I'm using.
When I ...
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Postfix: How can I handle incoming mail for a single address, not the entire domain?
I've gotten my employer to configure the company-wide Exchange server to forward [email protected] to [email protected], a host I control. So far, so good. My Postfix configuration ...
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Postfix relay to Office 365 - DNS configuration
To reduce the likeliness of email being flagged as SPAM, I believe these are the few things that should be done on email servers:
Hostname resolves to a valid IP e.g. mail.example.com to 1.1.1.1
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SMTP, snort: warning 124:3 attempted response buffer overflow
From time to time, I'm receiving a 124:3 warning "attempted response buffer overflow" from SNORT, while sending emails.
What could cause this warning? How can it be investigated? How can it ...
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Postfix 2nd domain
I have two postfix servers(virtual machines) on same host
1st domain = mail.xyz.org
2nd domain = mail.xyz.edu
I want to send mail from 1st domain to 2nd domain.
If i try, it gives error:
Recipient ...
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SharePoint SE not able to send automated emails
I have configured in SharePoint Administration the outgoing emails to an SMTP Server on Port 25.
The SMTP Server is a default setup with anonymous authentication which is the same on SharePoint, and ...
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IIS SMTP Relay to gmail fails occasionally
I'm using IIS SMTP relay to gmail to send outbound emails. I create this email text file with SSIS script task and place the file in the Pickup directory. This script runs every 15 minutes. It works ...
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Why am I getting Sasl errors when trying to authenticate to SES with Postifx?
I am getting these two errors in my mail logs:
Aug 25 22:51:23 ns1 postfix/smtpd[246267]: warning: unknown[94.156.102.101]: SASL LOGIN authentication failed: authentication failure
Aug 25 22:55:22 ns1 ...
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Two mail server installs (for two domains) on Windows VPS with one IP?
I'm referring to a VPS that's running software for mail services that's supplied by the VPS host. The VPS has 1 IP address and the mail software license supports only 1 domain.
I'm now adding a second ...
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How to configure postfix to reject emails which are pretended to be send from myhostname?
Suppose the Postfix mail service is serving domain @mycompany.com. Local network is 192.168.10.0/24. The attacker from Internet sends an email pretending it originates from @mycompany.com:
Received: ...
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Outlook cannot be configured to receive emails from an SMTP Server [closed]
I have installed an SMTP Server on Windows 2022 to on an internal network. So, outside emails. The server runs, and from another server using both telnet and Powershell I can mimic an email being sent....
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"550 5.1.2 Relay not allowed" Error returned when trying to send emails from my on-premises mail server
I setup an on premises mail server for my domain, to send and receive emails.
I've picked Stalwart mail server for this.
I deployed and configured the system, to the point which I am able to receive ...
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Exim4: (gnutls_handshake): timed out
I'm using Exim4 on the Debian server.
Debian:
Distributor ID: Debian
Description: Debian GNU/Linux 11 (bullseye)
Release: 11
Codename: bullseye
Debian kernel:
uname -a
Linux mail....
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Postfix smtpd_sender_restrictions with logical AND
I am using postfix, I need to configure sender based restrictions so nobody that is not authenticated & not part of mynetworks can send mail through this server,
this is my smptd sender ...
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Internal Address Spoofing using Outlook SMTP Server
Is there a way to harden Exchange Online to prevent spoofing of internal addresses using SMTP?
For example, if I connect to Outlook's SMTP server and issue the following commands:
HELO domain.com
MAIL ...
j4k3
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Postfix header_checks are ignored
I'm using Ubuntu 20.04. I installed Postfix (v3.4.13) with Dovecot (v2.3.7.2) a long time ago. Now, I want to overwrite the Message-Id header using header_checks. It's the first time I'm trying to use ...
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Windows and Ubuntu on same VLAN, but only Windows connects to telnet smtp.gmail.com 587
I'm having trouble trying to communicate with the port 587 on smtp.gmail.com on Ubuntu only, but the network and firewall teams (FortiGuard, I think), say that this is not a network nor a firewall ...
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Postfix - forwarding mail to an external email address
I'm not normally a Linux server guy: I'm a .NET programmer. However, I inherited a situation where there's a website hosted on a Linux server using Postfix on Webmin. They have several aliases set up, ...
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Exim: send emails from different ips and hostnames on the same vps
I have 2 ips on my server, I’m trying to set up 2 emails, one email sends from one ip, the other sends from the second ip. The first email is fine but I’m getting an error in mail-tester.com for the ...
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How to avoid reverse DNS errors
I am running a mail server (Exim) on a VPS (Ubuntu 22.04 LTS). I am able to send and receive emails without problem, but I do get the following errors from mxtoolbox.com:
Reverse DNS does not contain ...
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Sendmail unable to find recipient to send email
I am trying to set up sendmail for my server to send alert notification status. After searching for guides on the internet, I am still unable to send outgoing emails to my work email. from what I've ...
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Postfix - route mail based on Sender/Connecting IP?
I would like to configure my Postfix mail relay to route mails received from another server on my network to a specific upstream mail server. There are a wide variety of recipient and reply-to ...
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POSTFIX - sending mails. My mails sent outside bounce back
main.cf
compatibility_level = 2
command_directory = /usr/sbin
daemon_directory = /usr/lib/postfix/sbin
data_directory = /var/lib/postfix
mail_owner = postfix
myhostname = mail.aufy.pl
mydomain = aufy....
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Upgrade SMTP Server on Ubuntu Linux 18.04 to support TLS 1.2
Client has an intranet hosted with Apache on Ubuntu 18.04.
When I update an employees information through it, an email is sent, but it fails showing the following error:
(SMTP Error: 421 4.7.66 TLS 1....
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How to set up a postfix relay server for Google Workspace(gmail)?
There is a need to make a relay server for the company's corporate mail. The need arose due to the presence of some google ip in the spam lists, and this sometimes leads to the fact that letters end ...
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Not receiving any response from SMTP server after successfully connected via openssl or telnet
I am trying to set up my postfix using Gmail smtp relay server. I have set it up in other servers without issues, but I am having difficulty getting it to work in my work network.
I tested if there is ...
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What could be causing PowerMTA not to forward emails over port 465 SSL...?
We have a PowerMTA server that receives incoming e-mail. and forward it to external SMTP server that's not running PowerMTA i tried to do it using port 587 and port 25 both working fine and emails ...
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SMTP Relay - Keep sender SPF valid
We use a email setup (incoming mails) in the following order:
Internet -> on premises mailserver (=> attachment filter, antivirus, spam filter) -> forward to Microsoft 365 Exchange Online ...
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Postfix - Relay - authentificatin in Mysql
I tryed to manage with a postfix server, my goal is that :
When 1 special user ([email protected]) try to send mail, it will use routing (using a relay server is OK) but I don't understand how to send ...
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Redirect OR warn (during initial negotiation) SMTP submitters to use TLS on port 587 - leave 25 explicitly blocked by firewall for better security [closed]
I've managed to find a lot of closely related information, but not an answer truly addressing my question.
I am expanding on my homelab server, and have decided to use a small publicly hosted server ...
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Best Practice - SMTP Time Out
Good Day,
The question is quite straight forward. What should be a best practice to time out a SMTP connection on the RECEIVING side?
Background: We are currently having an issue with a sender that ...
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Postfix to gmail relay - preserving the sender's address
Relayed emails come 'from' [email protected], not [email protected], so I cannot reply.
I have several domains and am using Postfix to relay emails sent to [email protected] on to [email protected] as ...
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how to switch from outgoing port 25 to 587 in postfix
I would like to send a mail to a gmail address:
echo "This is the body of the email" | mail -s "This is the subject line" [email protected]
That is what I see in the logs
connect to ...
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SASL Authentication - Why is it taking so long to login to the authentication server?
I can't describe it properly, but I have a Thunderbird mail client, I use it to receive and send mail through a user I created and an available domain. I use IMAP and POP3 services there, I also have ...
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167
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iptables - port 25 not getting traffic even though default policy is ACCEPT and all rules are flushed
I am having a problem that's driving me up the wall. I have a server, where after several attempts at various iptable rules, I have flushed iptable rules and set default policy to accept.
The output ...
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Exim allow outgoing for specific domains
I am using Exim as MTA. I want if an email is sent out from my server, then the sender domain must be in the list "+local_domains", else it should be through the message "Not Allowed&...
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Dell IDrac8 SMTP setup diagnosis - RAC0225
I tried to setup the mail warnings on an IDrac8, it's not my first time, that's why I am wondering what I am doing wrong.
on this server it won't send mails with following error
"RAC0225 sending ...
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Postfix/Dovecot - Initial Config - Test Email Results - 554 5.7.1 Client host rejected: Access denied
I sent an email successfully. Can't say the same for receiving. When I attempt to, I get an email saying that the message was blocked with the following diagnostic code:
Diagnostic-Code: smtp; 554 5.7....
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Configuring Google Workspace (Gmail) to trust a Mail Relay via ARC?
I am building a system which modifies incoming emails body on the fly (for example, it deletes attachements with viruses). Of course, I break the DKIM signature when there is one. Is it possible to ...
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Using an existing Postfix + Dovecot server, how do I relay mail not intended for my configured domain?
I have a Postfix + Dovecot server that is receiving public mail and allowing folks to view their mailboxes using IMAP just fine for a particular domain (let's call the domain mail.acme.com). But, I ...
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opendkim-testkey: key not secure (file permissions are good and TrustAnchorFile config setting is set)
If I run sudo opendkim-testkey -d mydomain.com -s selector -vvv, I get
opendkim-testkey: using default configfile /etc/opendkim.conf
opendkim-testkey: checking key 'selector._domainkey.mydomain.com'
...
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Exchange Server 2019 can't send email on port 25
I have setup a windows server 2022 with Exchange 2019 and am unable to send out email because outgoing port 25 is blocked.
Vultr.com says they have removed the default SMTP block from my barebones ...
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112
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Why exim does not use TLS when sends email to remote SMTP?
Here what exim does when sends emails to gmail and other SMTP severs
Received: from ns01.virtex.kz (ns1.virtex.kz. [185.141.164.16])
by mx.google.com with ESMTP id i11-...
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What exactly is Return-Path and who sets it?
This article (https://www.sparkpost.com/resources/email-explained/return-path-explained/) explains "Return-Path" as follows:
When an email doesn’t make it to its intended destination, the ...
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174
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Gmail not detecting PTR record from vultr server
I have an SMTP server running on a vultr VM. I've set up the rDNS to point to my mail domain name mail.idimitrov.dev. The DNS setup points to that machine on ipv4 and ipv6 for mail.idimitrov.dev and ...
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Postfix white listing a badly configured server not working: Helo command rejected: Host not found;
My mail server configuration is rather strict and some times incoming mails from legit servers get rejected because the remote end has a configuration problem, a common one is the HELO hostname.
I ...
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