Questions tagged as ['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.
Score: 0
Adam Abel avatar
SPF records with a dynamic IP to a smtp relay with Office 365
mx flag

I'm helping out a client setup an smtp relay because our software is failing at times to send email when using the smtp server of and we have found that setting up a smtp relay via this link option 3 resolves this pro ...

Score: 0
SMTP relay with FQDN, but SpamAssassin marks FSL_HELO_NON_FQDN_1 and HELO_NO_DOMAIN
br flag

my mail provider ( offers an FQDN during the HELO/EHLO exchange (e.g. – which is seen by policyd-spf (s. below) – but SpamAssassin on a receiving server marks the relay as offering no FQDN or domain:

Feb  2 06:17:10 eden policyd-spf[478301]: prepend Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=;; envelope-from=xxx@posteo ...
Score: 0
Вукашин Лекић avatar
STMP connection error with roundcube
za flag

recently I was trying to install roundcube on my server and everything works fine until smtp test. When I try to connect i always get this error: SMTP send: NOT OK(Connection failed: Failed to connect socket: fsockopen(): unable to connect to ssl:// (Unknown error))

Syslog at time of connection:

Feb  1 11:14:35 mx postfix/smtpd[196497]: initializing the server-side TLS engine
Feb ...
Score: 0
Why does Outlook only connect to my server but not send any email?
se flag

I don't have any problems receiving email from Gmail, or any of the mailing lists that I've signed up for, but for some reason Outlook refuses to send any email to my mailserver.

_handle_client readline: b'EHLO\r\n'                                                                                                           │
('', 55618) &gt ...
Score: 0
Zimbra Setup, can receive emails, but I cannot send emails
cn flag

i installed zimbra on my Cloudserver (Digital ocean) i can receive emails from other external emails but sending is an issue, I have also set up DKIM, SPF, DMARC for the emails but i still cannot send out emails. Anything seems to be the issue? Please what are possible Resolutions/?

Score: 0
manifestor avatar
SSMTP: Map local user (UID greater than 1000) to an external email address
mp flag

I've configured SSMTP to send system messages for users with a UID < 1000 in /etc/ssmtp/ssmtp.conf:

If I send an email to root (echo test | sendmail -v root) for example it gets properly delivered to (as per root in /etc/ssmtp/ssmtp.conf).

However this doesn't work for user accounts with UIDs greater than 1000. If I send an email  ...

Score: 2
DKIM: Can I safely add a DomainKey policy record without breaking existing email?
jp flag

I need to setup DKIM to validate an email provider we are using. In the provider's documentation, they require us to add two records, a selector record and a policy record, like this: TXT "k=rsa; p=mykeyhere"  TXT "t=y; o=~"

I'm concerned about adding this new policy, because we have quite a few DKIM selectors setup in our DNS zone already, wit ...

Score: 0
WebApp needs to send emails via mail account
kg flag

I have a web app running on a shared server account for the domain The web app needs to send the occasional email to the app adminstrator.

The domain is using as the email server.

How can I either:

a) Configure the web app to send emails via an mail account (can you point me to the instructions/settings to configure this?), or

b) Configure the included mail ...

Score: 0
VaNa avatar
postfix: how to force IPv4 through SMTP?
co flag


I have successfully set up a Postfix mailserver with an SMTP interface, set up DKIM, DMARC, SPF, all that stuff.

But I had a problem when testing the delivery of emails to Gmail.

Namely, SPF would pass if I sent it by the sendmail command from the server (some of the ARC-Authentication-Results header content of the delivered message in Gmail):

spf=pass ( domain of redacted@example ...
Score: 0
Sami Arja avatar
Postfix / mailutils Mail appears to be sent in logs, but not in the mailbox
cn flag

I've seen few of this question here but I couldn't find a solution for it.

I'm currently trying to set up Postfix with mailtutils, but I can't see my incoming emails in my mailbox, so I am not sure if there is something wrong in the process.

The mails I sent to my mail account appear to be sent in the logs as delivered but they are not received into the mailbox, not even the spam folder. The logs ar ...

Score: 1
Require authentication from subset of mynetworks in postfix
cn flag

Is it possible to configure smtp for postfix to require authentication, (e.g. with smtp_sasl_auth_enable = yes), for certain IP ranges but have other ranges un-authenticated?

For our local network we want hosts to be able to relay through the smtp servers without authentication, including sending externally. That network range is listed in mynetworks.

But for other ranges, not on our network but in

Score: 0
Xsnipe 1231 avatar
Email Server with API calls
my flag

I am new to the world of Web Email and domain hosting. I was looking into projects like and In these applications I can receive an email address, receive emails to those email addresses, and then delete the email from a simple python client using API calls to their API's. I want to replicate something similar using my own domain name(I have not regist ...

Score: 0
Compared to SPF MAIL FROM checks, what are HELO checks good for?
cn flag

I’m starting with SPF on my (email) domain. (No DKIM or DMARC yet.)

I see little usefulness in HELO identity checking in SPF and am thinking about setting the HELO identity to my domain (instead of the hostname) or the IP of the machine.

Apart from the following points, what is SPF HELO checking good for? What points stand against using IP or domain as identity in SMTP clients?

  • it is against (the s ...
Score: 0
Sasha Dzuruk avatar
Setup DNS records for SMTP send-only server
do flag

I have website on hosting with domain I have DNS record for MX(10) A XX.XX.XX.XX TXT v=spf1 +a +mx +a:hosting.server ~all

All incoming mail recived by hosting server.
Now all mail work over hosting server. I want to create SMTP server to send-only mail. I use Postfix. And create DNS record for A XX. ...

Score: 0
Relay access denied error attempting to setup relay to another SMTP server
cn flag

I am attempting to setup 2 SMTP servers behind one firewall. One server for and another for I want to configure the server for to accept mail for and forward it internally.

I have added the following setup in /etc/postfix/ on

transport_maps =
    proxy:mysql:/etc/postfix/mysql/transport_maps_user. ...
Score: 0
Sem van den Broek avatar
Iptables + telnet not blocking ports
lr flag

I have a Debian server from which I want to block all incoming and outgoing ports (especially all outgoing email ports), except those that I specifically add in iptables. The current setup I have is working and seems restrictive enough, but when I start up a telnet session to test for example port 25 for smtp it just seems to connect without problems, even though I did not specifically open port 25 a ...

Score: 0
zumm avatar
How postfix actually treats relocated_maps?
cn flag

I'm close to understanding it, but one thing in documentation makes me unsure.

At first, lets take a look at postfix architecture from docs. There are two stages: receiving and delivering. During receiving stage mail is stored in incoming queue and smtp client is notified about successfully enqueueing.

Also documentation says relocated_maps is treating by trivial-rewrite ONLY during delivering stage. And  ...

Score: 0
Lawrence avatar
.NET program sending of email not working on client server only
gb flag

I've originally asked this in SO but it seems this is a more appropriate place.

Basically, I have a program that sends email which works on my local machine and on our company's server. However, it's not working when deployed on the client's server.

The program cannot connect to the smtp server for some reason. Here is the exact error:

System.Net.Sockets.SocketException (0x80004005): A connection attempt ...
Score: 0
Stand alone SMTP server as Email Server in Windows 2012
si flag

I want to configure an email server using SMTP Server set up in a Windows 2012 node.

I could see that, its possible using hMailServer,


Can SMTP work as a email server..?

Would this be possible to create a local domain in SMTP Server set up ..?

Would this be possible to register email ids in SMTP server set up ..?

Is it possible to send and receive emails, by connecting mail clients to it..?

Foll ...

Score: 0
Richard Olthuis avatar
How to force postfix to use smtp relay
fr flag

When I execute, the following line postfix uses my sendgrid relay server

echo "Subject: sendmail test" | sendmail -v

But when I execute the sendmail function via the PHP script it won't send it to the relay server. Look like it want to distribute it locally

Any thoughts on how to force postfix to use the smtp relay option

  • Update

It looks like postfix is timing out on STARTTLS, I have  ...

Score: 0
ehammer avatar
Graylog Email Alert Password Not Working?
us flag

I recently changed my gmail password and changed the password in server.conf as well, but now graylog's email alerting fails with:

Sending the email to the following server failed : (javax.mail.AuthenticationFailedException: 535-5.7.8 Username and Password not accepted. Learn more at 535 5.7.8 h12sm2292608qkp.52 - gsmtp )

Here are th ...

Score: 0
Byte legion avatar
Trigger a python script when postfix hold an email
de flag

i have a python script and i want it to run each time postfix holds and email i managed to hold emails based on some patterns using regular expression under /etc/postfix/ and i want to run this python script each time an email is holded. i did my research and i found it this potential solution Postfix does not trigger my before-queue milter script an i tried this:

smtp      inet  n       -       ...
Score: 0
F. E. avatar
Why is UFW blocking the smtp-plugin from Dokuwiki
bv flag

I have on a virtual server (Ubuntu 20.4) Dokuwiki (2020-07-29 "Hogfather") with the SMTP plugin (Last updated on 2020-11-21) installed. My pages are delivered HTTPS encrypted, using certbot.

I want to use the SMTP plugin from dokuwiki with an existing mail server from my provider. I filled in the necessary credentials: username, SMTP server address, port 465 and SSL.

I get this debug message from do ...

Score: 0
Error in config, reported only as syntax error
cn flag

I have a simple config (based on googling and copy paste) that contains an error, I don't know how to proceed.

I would like to forward all mails received to an smtp-server that requires username+password+TLS

The config:

listen on port 25
action "relay" relay host "smtp://" mail-from ""
match for any action "relay"

Apparently there is an error on line 2:

Oct 13 21:08:56 raspb ...
Score: 0
YaRmgl avatar
SMTP - How to use a different IP for incoming emails
it flag

I have a send-only postfix email server where I sent emails via a command line tool I want to be able to receive emails on a separate provider so that the staff can access the inbox

I have a temporary solution, it is to receive emails on a subdomain:, but I want to use the main domain

Score: 0
Exim catch_all_outgoing not working? redirect all outgoing emails to single one
eg flag

I'm researching around to see how I can configure Exim to reroute all outgoing emails to a single email address (possibly external), to be used on a development server when during tests I don't want to accidentally email real people.

It seems like something that should be simple to do, and apparently there's the catch_all_outgoing router as a solution, but it doesn't work as it seems is deprecate ...

Score: 0
Is this possible with Sendmail?
om flag

We are migrating to a new SMTP host, and have found some issues with some of the sendmail instances I have inherited. The new SMTP host requires all "from" addresses to be from domains we are verified owners of.

I have spent a couple of days trying countless results from google without any results, so thought I would make a post since this seems too specific.

The situation: We have a sendmail instan ...

Score: 1
Patrick avatar
Office365 Connectivity Issues
mx flag

I've got a 3rd party who host a system for us, it has a function to send a small number of emails for us, less than 100 a day, so we simply supplied an Office365 user to them which has been working for ages.

Last night this stopped working. The interface I can see is simply returning Message could not be sent. Mailer Error: SMTP connect() failed. (PHPMail)

The third party is massively dragging it ...

Score: 0
Byte legion avatar
Postfix After-Queue Content Filter full example
de flag

i'm trying the Simple content filter example: i followed the steps mentioned here

but in line 24 of the content filter that can be a simple shell script like this

you need to specify your content filter

my question is :

is there any full example with a content filter ( line 24) that i can work with ?

 1 #!/bin/sh
 3 # Simple shell-based fi ...
Score: 0
Sam avatar
SMTP authentication issues with Postfix Dovecot
in flag

I had bought a domain and a VPS, and I used iRedMail to set up a mailserver.

Not wanting iRedMail to mess up with my Nginx, I decided to install Nginx and Roundcube by myself. However, it says the SMTP server doesn't support auth. SMTP is all right.

[02-Oct-2021 23:40:16 +0000]: <5gl20r7b> PHP Error: SMTP server does not support authentication (POST /?_task=mail&_unlock=loadin ...