Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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.

0
votes
0answers
18 views

What email headers are useful for determining if my email account has been compromised?

I've recently received a lot of spam replies (automated replies from users, and rejections from mail servers) to a certain email address. I've taken the obvious precautions of changing passwords, and ...
-2
votes
0answers
17 views

High-level requirements for starting construction of email server from scratch [closed]

I would like to know how to deploy something like SendGrid to Google Cloud. That is, I don't want to use SendGrid, I want to build something like SendGrid. I saw How to setup a mailserver on Google ...
0
votes
1answer
25 views

PHP mail() function working from command line but not working with apache

My problem is that php script which has to send mail doesn't send it if I run it in browser, but works in cli. This doesn't help PHP's mail() function working in CLI but not in Apache In both /...
1
vote
1answer
35 views

Sending email using a third-party smtp requires an mta?

I have a G Suite account and want to use the Google's SMTP to send out emails from my server. How can I then send emails from Linux's CLI? I read with some research that I need a program such as ...
0
votes
0answers
34 views

PowerMTA routing loop detected

I am facing with an issue, I have spent a day trying to solve it. Everything works fine except sending mail between mailboxes of the same domain configured as a virtualhost. Here is my configuration ...
0
votes
1answer
19 views

cdosys mail from classic ASP

I am supporting a customer running a proprietary Content Management System written in Classic ASP. Certain pages use the cdosys message routine to send email. This is used to report page errors back ...
0
votes
0answers
48 views

Connect / disconnect unknown postfix log

I'm checking the logs and i found these lines in maillog postfix/smtpd[12135]: warning: hostname mta9.imxonlines.co.za does not resolve to address 91.212.150.89: Name or service not known connect ...
0
votes
0answers
43 views

SMTP recipient's server gives 5.0.0 Service unavailable for some messages but not for others [missing SRS?]

I run a CentOS 7 sendmail SMTP server. For some addresses (a@myclient.com), a virtusertable entry causes my server to forward messages addressed to that address to the client's ISP (charter.net) or ...
0
votes
1answer
23 views

mail server proxy suggestions

Currently we i have a mail server for example "mail.example.com". This is a dedicated email server and we are looking to replace it. We are considering outsourcing the email management through ...
0
votes
2answers
30 views

Can SMTP retries come from different IP addresses?

I have a FortiMail with Greylisting turned on. The idea is that only after a valid SMTP retry, an email will get released. However, it appears that for a large email provider like outlook.com, ...
2
votes
0answers
62 views

Why is Exchange 2010 SMTP not rejecting external messages to internal-only groups?

TL;DR: How do I make sure that the SMTP server doesn't accept external messages for distribution groups that are set to require authentication? I have an Exchange 2010 server that has multiple ...
0
votes
0answers
15 views

Squirrelmail cannot send mail | SMTP setting

I have a working Postfix+Dovecot email working and works fine with thunderbird email client. However, while using squirrel mail,I can only receive email but cannot send. It seems the squirrelmail ...
0
votes
1answer
35 views

Should I set up my Postfix send-only server to send as a subdomain?

Scenario: I own the domain example.com. I am signed up with an email provider, and configured my account as a catchall for *@example.com. I use the email dude@example.com. I have a VPS running Ubuntu ...
0
votes
1answer
49 views

What else to check to find why emails are not delivered?

Our email messages are not delivered. We have done some debugging but have not found any issues. When we send an email using a simple test script PHPMailer reports success and the logs indicate the ...
0
votes
0answers
31 views

What does the “Retain internal Exchange email headers” setting in Office365 connectors do?

In Office365, when creating a mail connector, one has the option of enabling/disabling Retain internal Exchange email headers. The setting has a link to documentation but it may be outdated, as ...
1
vote
0answers
23 views

Can't find the IP address of a Saslauthd login attempt

I need help locating the origin IP from this error messages/ login attempts: From the 'sasl auth daemon' via Logwatch: pam_unix(smtp:auth): check pass; user unknown pam_unix(smtp:auth): ...
0
votes
2answers
34 views

Relaying mail for a machine with port 25 blocked [closed]

I recently moved and had to start using a new residential ISP (my old one doesn't serve the new address yet). To my dismay, the new ISP has no option of unblocking the TCP/25 port even when you buy a ...
0
votes
0answers
27 views

Can we use nginx proxy to hide origin server exposure from external smtp like gmail?

So if possible, I'd like to hide the exposure of my origin server ip when sending SMTP emails for example from Gmail because I have been DDoSed several times just because they get IP from email. I ...
0
votes
0answers
144 views

SMTP authentication failure after TLS cert

yesterday I set ssl certificates for our company webpage and webmail client using Let's Encrypt Authority. After the succsses of this procedure I've tried to add the same certificate inside the ...
0
votes
1answer
40 views

Strange mails from my email server

My postfix server and website (WordPress, Apache) resides on the same server box. 2 days ago, we decided to use 3rd party smtp relay host for our mail server. All the DKIM and spf records are in place....
0
votes
1answer
60 views

How can I decide which emails go through SMTP relay?

I am using postfix configuration that use SMTP relay on Sendgrid service like this: smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd smtp_sasl_security_options = noanonymous ...
1
vote
1answer
91 views

How to internally load balance SMTP?

We are using IIS SMTP to send out Email for a web application. If I stand up another server what would be the best way to load balance these internally so they both get used and if one goes down the ...
0
votes
1answer
42 views

You apparently created more than one SPF record on your DNS

I am getting this error from mail tester What we retained as your current SPF record is: v=spf1 include:sparkpostmail.com ~all More information about this error: You apparently created more than ...
2
votes
1answer
18 views

Use AWS SES as an outbound email gateway

I would like to re-route all my company outbound emails through AWS SES SMTP, do some processing to the email there, then let it go out once done. Is this doable ? This is doable for incoming emails ...
0
votes
0answers
26 views

How to find out how spam is being sent helo=127.0.0.1

I have a mail server which is rate limiting outbound mail using postfwd rules as follows: id=R005; action=dunno ; client_name=host\.mydomain\.com\.uk$ id=R010; sender=~/.*/; action=rate(sender/100/...
0
votes
1answer
32 views

Mail server - relay with TLS and authentication

I am working with postfix and dovecot and I can't seem to find out anywhere how to create this setup: 1) allow submission of emails from outside (telnet) where the sender domain is the local server ...
-1
votes
1answer
54 views

How can i redirect smtp port 25 to port 465 [closed]

I have Exchnage server ,I can receive emails But I can not send emails out of the domain because Port 25 is block in ISP How can i redirect smtp port 25 to SMTPS port 465 ?
1
vote
1answer
40 views

Should I enable port 587 for mail relay access?

I run a virtual email server using Postfix that forwards emails addressed at domain.com to specific Gmail / Hotmail accounts. This same server also acts as a mail relay, and uses saslauthd to allow ...
1
vote
1answer
425 views

Windows Server 2019 built-in SMTP server: Emails stuck in queue and “The remote server did not respond to a connection attempt” in event log

I'm setting up a new dedicated server using Windows Server 2019. It's replacing an old one based on Windows Server 2008 R2. I have had the built-in SMTP server running on the old server with no issues....
0
votes
0answers
21 views

How to allow only specific sites to make authenticated SMTP request using IBM Domino

I am using Internet site documents and have SMTP Inbound Site document that have TCp authenication enabled for both Name & password and Anonymous In the server configuration document I have added ...
0
votes
0answers
25 views

Sending mail with sendmail - not sending

I have apache2.4 web server with PHP on Debian server. I noticed that my PHP mail() function doesn't send any mail. Looked at the spam folder as well. I cleared all the mail logs on my server and ...
-1
votes
2answers
98 views

Is someone able to sniff our corporate emails?

To put the long story short: we discovered someone is able to access some of our "secret" links we do send to our clients over email. The links are highly secured with hashes, extremely difficult to ...
0
votes
2answers
33 views

Windows machine to send email

What software/package required on a new Windows machine (say Win10) to send email. My understanding is that it needs SMTP client kind of software installed to communicate with an SMTP server to able ...
1
vote
3answers
34 views

Sending email to a server that requires a login [closed]

I'm trying to understand how SMTP servers work in production environments. I am wondering how email can be sent from server A to server B if server B requires a login. A real life example of this ...
0
votes
1answer
49 views

Postfix reply from catch-all received address

I have a postfix installation where all addresses are virtually mapped to one user, i.e.: >cat /etc/postfix/virtual @mydomain.com myuser What I want is the ability to reply to emails that are ...
0
votes
0answers
37 views

setup smtp(without domain) locally for another app (sandstorm.io)

Disclaimer: I have barely any infrastructure knowledge, so maybe the obivous already works. I am trying to setup sandstorm.io on my local machine for testing purposes. It needs an SMTP server to send ...
1
vote
1answer
58 views

Is it an issue when I change the IPv4 address of my SMTP server?

I have a postfix/dovecot setup for a personal mail account. It's really just a one-man mail setup. Now I want to move my setup to a new VPS which means it'd get a new IPv4 address. My concern is ...
0
votes
0answers
38 views

Whitelist or rewrite recipient address in postfix

I am managing a website. In production environment, all the emails are relayed through a central postfix using amazon ses as smtp relay. The reasons to add postfix in between and not use ses directly ...
1
vote
1answer
99 views

Sendmail in FreeBSD send with external SMTP without auth

I'm sorry if this might sound confusing at first. My brother asked me to make a web server for him because he wanted to self host his own website and not use a hosting service anymore. The problem ...
-1
votes
2answers
358 views

how to set the FQDN on 2008 R2 server using the ip address?

From what I understood from my searches, to avoid the "Access denied - Invalid HELO name (See RFC2821 4.1.1.1)" when sending emails using the SMTP on a 2008 R2 server, its FQDN must be set and to ...
0
votes
1answer
49 views

Best way to restrict/manage PHP apps to use my postfix?

I want to allow PHP apps to send mail but under very restricted conditions. And I don't want to allow sendmail-like command for PHP apps (I'm using chrooted PHP and it's too much headache), thus I ...
1
vote
1answer
20 views

Diagnose Avaya IP Config to SMTP

We have 10 phone extensions that instead of gettings messages on the phone, we configured the Avaya IP Office to forward messages to a specific email for each extension. The SMTP server adress is ...
0
votes
1answer
195 views

Connection closed by foreign host (postfix)

Tried to test my smtp server (centos server), I am using telet at centos When I tried to test using code: telnet 127.0.0.1 25 Trying 127.0.0.1... Connected to 127.0.0.1. Escape character is '^]'. ...
0
votes
0answers
84 views

Mailbox name not allowed. The server response was: 5.7.1

I setup postfix on centos 7 server, and when I tried to send mail using that server I am receiving errors as below: Mailbox name not allowed. The server response was: 5.7.1 : Sender address ...
2
votes
1answer
39 views

Mail blocked from Windows Server 2016, but not since 2008

Good Morning: I'm running exactly the same script from two different virtual machines: The first in Windows Server 2008 R2 The second in Windows Server 2016 Features The SMTP is an external ...
0
votes
1answer
121 views

How to enable SMTP on Windows Server 2016?

I recently purchased VPS service to allow me to host a site. My mail provider is zoho.com. In order to get it to work, I would need to add 3 entries under Mail Exchange records (MX Record) as the ...
3
votes
1answer
53 views

High volume e-mail delivery to internal recipients on Google G-Suite

Attempting to deliver more than a few hundred e-mails per day via SMTP to our own employees on Google G-Suite tends to cause significant delays due to arbitrary quota limitations on the Google side. ...
0
votes
0answers
20 views

SystemArch: How to proxy multiple physical mailservers behind one DNS?

Assuming following system architecture: internet | smtp.mydomain.com (TLS/SSL enabled SMTP-proxy?) | +--------DMZ----...----+ | | ... | ...
0
votes
1answer
32 views

Postfix relay authentication for both server and client

I built a postfix relay several years ago that relays through office365. This is limited to hosts on the VPN, but now want to provide a public IP and allow remote printers to relay through postfix for ...
0
votes
1answer
25 views

Need more information about exim4 log

Sometimes when I try to send a mail, I can see in exim4 mainlog,a line like this : address_mail R=dnslookup_users T=remote_smtp defer (98): Address already and the mail is put in exim queue, why ? I ...