Questions tagged [smtp]

SMTP is a protocol built upon TCP/IP, used for outgoing email transmissions, and email relaying. It uses ports 25 (clear) and 465 (SSL) by default.

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46
votes
7answers
63k views

Lightweight outgoing SMTP server

What do you use as a lightweight SMTP for outgoing e-mails only? I am running an app that sends e-mails via SMTP when events occur once in a while, and I don't need a fully featured e-mail server. ...
72
votes
6answers
259k views

Can I set up system mail to use an external SMTP server?

Is it possible to set up system mail on a linux box to be sent via a different smtp server - maybe even with authentication? If so, how do I do this? If that's unclear, let give an example. If I'm at ...
2
votes
1answer
3k views

Trying to send multiple text attachments via mail message

Running this script on: "Red Had Enterprise Linux Server release 5.11 (Tikanga)" Mail is: version 8.1 6/6/93 (appears quite old). Have tried various things and cannot seem to get this to work.. ...
22
votes
3answers
69k views

How to “close” open ports?

A few days ago I started to care a lot about my data security, I end up nmaping myself with: nmap 127.0.0.1 Surprise, surprise, I have lots of active services listen to localhost: $ nmap 127.0.0.1 ...
6
votes
2answers
4k views

Postfix: prevent users from changing the real e-mail address

My postfix e-mail server is finally working well. Now, I need to prevent users from forging their e-mail addresses in the client programs in the "from" field in the header, because a user can send ...
0
votes
1answer
6k views

setting up a relay port for postfix smtp on CentOS 7

A CentOS 7 server has postfix, dovecot, and mailx installed. I am able to make an IMAP connection to the server from my remote Thunderbird client running on my local devbox. But I am not able to ...
13
votes
1answer
51k views

How to Allow Outgoing SMTP on iptables Debian Linux

If I choose to allow all traffic on the OUTPUT chain (iptables -P OUTPUT ACCEPT) mail sends fine. As soon as I lock down my server with these rules, outgoing mail stops working. All else works though, ...
2
votes
5answers
34k views

Mutt not sending email when specifying smtp server

I am trying to use mutt as my email client, and it works fine for my gmail account. But when I use my work email, it does not send the emails. It doesn't give any error, it just doesn't send them. The ...
8
votes
8answers
64k views

Helo command rejected: need fully-qualified hostname Error

My mail server is in some blacklist cause of spams. I reconfugured postfix. Aften then My customers get this error they can't send emails. 404 4.5.2 <PLLAMNAZIFE>: Helo command rejected: need ...
0
votes
0answers
86 views

How to install Postfix in an all default way (no setup wizard) and to be used with no email DNS records?

The following question is a follow up to this question. In a latest Debian 9 stable I desire to install Postfix to send email from my machine to my very own Gmail account by the quickest install ...
4
votes
2answers
2k views

What is the correct helo for a smtp server that does not receive mail and does not have a FQDN?

What is the legal and correct helo for my SMTP server. Out going email only. Behind a NAT with no inbound ports open. SMTP server does not have a FQDN. Send mail for 2 different domains We are a ...
3
votes
1answer
3k views

assigning two ports to one service in firewalld

Is there a way to assign two ports to the same service in firewalld? For example, I would like for the SMTP service to listen on both port 25 and port 465. My first instinct is to change /usr/lib/...
2
votes
2answers
2k views

How to send mail from a remote SMTP host?

I have Postfix suite installed locally on Ubuntu 10.10. I can send/receive mail to my local address, e.g. user@local.com. I'm given credentials to a remote mail server mailbox, e.g. other@remote.com....
2
votes
2answers
4k views

Ubuntu 18.04: Error with mailx smtp - mailx: unrecognized option “-S'”?

I was trying to send an email to multiple persons using mailx (mailx (GNU Mailutils) 3.4). I did that successfully on a previous version of Ubuntu, v16.04, and the script was working fine. Now I have ...
2
votes
3answers
736 views

Can I send email in the background in Mutt while still being notified of errors?

Removing mutt's send delay I originally used mutt's built-in SMTP MTA. However, there is a considerable pause after hitting send. This can be disabled by using an external MTA with set sendmail_wait=-...
0
votes
1answer
438 views

Is this the correct SPF DNS TXT syntax to allow the existing email servers (DNS MX records) and to authorize the new smtp server ip-address?

v=spf1 +mx ip4:65.1.2.3 -all Domain DNS TXT records to change: product1.com : sales@product1.com otherproduct.biz : sales@otherproduct.biz Information: Both domains have DNS MX records, and mail ...
0
votes
1answer
209 views

Exim dnslookup, priority and “blacklist” (not really blacklist)

I'm investigating how exim deliver mails, and I came to the conclusion that when the server is going to send a email exim makes a nslookup and get the higher priority (lower value) MX record and tries ...
-1
votes
3answers
3k views

unable to view postfix email from centos 7 command line, why not?

I have postfix installed on a development box and I used the parameters from this other posting to configure postfix to work on localhost only. But the other posting does not explain how to send ...