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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1answer
107 views

Sendmail (or postfix or somebody) not speaking SMTP

I've got a Linode Debian server which tries to send email (normally through PHP, but mail from the command line doesn't work either). But the mail never arrives successfully. My two clues from people ...
0
votes
2answers
74 views

Which Exchange 2013 Role will allow mail relay

We have a service that connects to our default receive connector in exchange, which relays the message to external users. Currently I have configured the service to use my DA account which assigned ...
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votes
2answers
83 views

Exchange server accepts email without authentication. Is this a misconfiguration?

I am a user on a network with an exchange server and there is an HP scanner/email machine that can send emails with scanned docs as an attachment from any email address without authentication so I ...
0
votes
3answers
595 views

Certificate on port 25 when trying to secure SMTP with POSTFIX

Background I think I am close to getting my POSTFIX setup to my liking. I've run some SMTP online checks and my SMTP passes all the basic security tests. I get a certificate warning in Thunderbird. ...
0
votes
1answer
54 views

Exchange 2013 SMTP reply error not being sent

We are scanning to our exchange 2013 server from a scanning application that uses smtp, in the past when the mail exceeded the smtp size limit it would send an email with a link instead of the scanned ...
0
votes
1answer
58 views

Postfix with external SMTP

I'm trying to install Request Tracker and configure it to use an external SMTP server to sent mail notifications. I've already put postfix to send emails using this tutorial, but it keeps sending then ...
0
votes
2answers
54 views

Make exim accept mails to be redirected only when they can be sent

I run a small mail server with all the usual functionality: Sending of local mail, receiving mail for local folders, redirecting mail according to alias and a mailing lists. The redirections go to ...
1
vote
2answers
230 views

Incoming mail rejected with “Invalid HELO name” [closed]

I'm unable to receive important emails from someone, with this error in my exim log: 2015-01-21 11:30:16 H=xxx.xxx.xx.xxx [xxx.xxx.xx.xxx]:50143 X=TLSv1:AES256-SHA:256 rejected MAIL ...
0
votes
0answers
136 views

The Remote Certificate is Invalid According to the Validation Procedure [closed]

Seeing this error on all but ONE machine in the building. One PC is accepting the certificate and all clients are denying it. Any reason this wouldn't be domain wide?
0
votes
1answer
151 views

Postfix: delivering “local” mail to GMail, but sending other mail

I need to set up a server to send messages to a few different people automatically. The recipients are at two different domains, let's say mydomain.com and otherdomain.com. The messages need to come ...
2
votes
1answer
194 views

IIS SMTP TLS encryption issue

I enabled TLS in IIS SMTP Virtual Server with a self-signed server certificate. Made sure that the certificate has the FQDN of the server. Checked the TLS encryption checkbox in Virtual SMTP > ...
0
votes
1answer
198 views

Postfix not sending authentication when relaying to local smtp server

I have been trying to get my postfix server to relay all of my message to a local SMTP server. As far as I can tell I have everything set up right, but I get a 550 Authentication error. My local SMTP ...
0
votes
1answer
256 views

Postfix - SMTP mail delivery failed with “Connection timed out” error

I have installed postfix mail server in Ubuntu machine. I am facing some issues with the mail sending to other domain mail servers (Google, Yahoo, Outlook...). I am using virtual domain to send the ...
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votes
1answer
151 views

How does zimbra procedes with sending email to the same domain if zimbra is configured to relay the messages to a proxy server

Does zimbra relay emails that are from the same domain as the expeditor or the emails are send directly to the zimbra mailbox without going trougth the relay server? I have a mail p1@example.com and ...
0
votes
1answer
2k views

Windows Server 2012 R2 IIS SMTP Server Will Not Send Emails

I have an existing SMTP server on our network that is used to send emails from a variety of printers, applications, etc... I have installed the IIS SMTP Server on a new Windows Server 2012 R2 server ...
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votes
2answers
67 views

Is it possible to use Gmail for transaction email? [closed]

We currently use Gmail for our support email. For transactional email (reset password, etc) we just use default Linux Postfix server on our Amazon Web Serivce EC2 instance. My question is would it ...
1
vote
0answers
80 views

SMTP delay when sending mail from Centos

I am encountering long delays when trying to send mail with swiftmailer using 1and1's SMTP server. there is a 19 second delay everytime as shown below by tcpdump: 21:54:50.784747 IP (tos 0x0, ttl 64, ...
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votes
1answer
159 views

hotmail.com - Unrouteable address

I'm using Exim on my mail server, and trying send email to someuser@hotmail.com address. I got email from this address, and make "replay" then. But - I have return from my SMTP with Mail delivery ...
1
vote
1answer
130 views

Catch all emails and pipe them all to a script with postfix

I realize this question was asked and answer before. Here's what I have done. Created a catchall address and user. Here is my /etc/postfix/virtual file. @example.com catchall Added it to main.cf. ...
0
votes
1answer
63 views

Reliable/robust method of ripping attachments from a POP/IMAP/Exchange mailbox

I'm looking for some fresh ideas after a bit of a google and would love your opinion: I have an email address hosted in exchange that will receive attachments on a regular basis. I would like a ...
2
votes
2answers
303 views

The benefit of different SIP and SMTP domains?

I was wondering if there was an advantage of having a different Lync SIP domain name from the Exchange SMTP domain name? I could see the disadvantages, but I'm trying to understand the real world ...
0
votes
1answer
63 views

Postfix check hosted sender domain [closed]

On my server I have this problem: there are mails sent from, example, johndoe@domain.com even if domain.com isn't hosted on my server. And, obviously, there is no johndoe@domain.com among the e-mail ...
2
votes
1answer
621 views

cannot find postfix/mailx email in maildir, why not?

In a CentOS 7 development machine, I have configured postfix to allow emails to be traded between localhost addresses. Mailx is also installed. I am able to send email, and the log files indicate ...
2
votes
2answers
341 views

Postfix & Amavis - Use UNIX Soket for Communication

I currently using a complex mailserver setup using Postfix, Dovecot, Amavis and Spamassassin. Everything works fine but I want to improve the Postfix-Amavis-Communication. At the moment, postfix will ...
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votes
1answer
70 views

Secure cloud to internal Mail setup using UUCP or something more modern

Some of our Linux servers are going to be moved out into a cloud. But the servers need to be able to email our users internally and are required to use our domain name as sender. The server cannot ...
0
votes
0answers
149 views

Local Xeams standalone server not sending emails?

I want to setup a Ruby On Rails development environment where I can develop an application that can send emails. I can use the smtp.gmail.com free server but I do not want to use it, but rather I want ...
1
vote
2answers
108 views

should multiple servers each run a full postfix stack, or use one central mail server

I have a collection of servers that will each have their own tasks. web server, billing server, game servers. Each of which will need to either send customer facing email, or simply send it's system ...
1
vote
1answer
37 views

Add an alias in postfixadmin with smtp access

I want to create a second identity support@mydomain which I want to send emails from. My mailbox is info@mydomain, so receiving emails should still go into this same info@mydomain mailbox. In my ...
3
votes
1answer
196 views

Relay email for some addresses, forward for others with Postfix

I administer a domain (let's say example.com) for a client who uses an Exchange server at an external service provider for email. So I made the MX record point to the Exchange server, let's say ...
7
votes
1answer
3k views

Roundcube & Postfix SMTP: SSL routines:SSL3_READ_BYTES:tlsv1 alert unknown ca:s3_pkt.c

I have a Postfix / Dovecot / Roundcube setup that I use personally, as well as provide to other users. I am attempting to transfer this entire setup to a new box, but having some issues. Mail ...
1
vote
1answer
151 views

Are “via” and “on behalf of” headers determined by both DKIM and SPF?

To get rid of the "via" and "on behalf of" headers in Gmail and Outlook, do I need to set both the DKIM and the SPF records, or are DKIM records enough? We recently changed our SMTP provider from ...
1
vote
2answers
1k views

postfix fails to send mail with “fatal: unknown service: smtp/tcp”

I have installed postfix, and when I tried to send a mail to gmail it told me that it has been sent, but when I checked my inbox in Gmail I didn't saw it. This is how the connection looked like: $ ...
1
vote
1answer
121 views

using a self-signed certificate with Amazon SES

I'm configuring Amazon Simple Email Service, I get to the point when I try to send an email and I get the error message: The SMTP server requires a secure connection or the client was not ...
1
vote
1answer
3k views

450 4.7.1 Client host rejected: cannot find your hostname

I have a Postfix/Dovecot email server which fails to deliver emails to some addresses. Here's an example of what is says: <xxxxx@board.com.ua>: host mail.da.net.ua[91.213.154.4] said: 450 4.7.1 ...
1
vote
1answer
454 views

Postfix DSN code explanation

Since few days ago I was unable to receive automatic emals sent from my PHP application. When I use Terminal to send an email to my @gmail address, everything works. When I try to send it to my ...
5
votes
1answer
64 views

Is Exchange 2010 compliant with RFC 3848

I have looked up Exchange 2010 Support for RFC Standards but do not see RFC 3848 amongst the supported standards. I do see RFC 4954 listed, which 'recommends use of RFC 3848 transmission types', ...
1
vote
1answer
203 views

postfix discard or change Message-ID header based on another header line

I want to change the Message-ID header or better yet, discard it. I know everyone is going to ask "Why would you want to do that?" because I know it sounds weird to even write it. Well I am ...
3
votes
1answer
199 views

Postfix SMTP relay server

I use gmail to receive e-mails both from my gmail address and my own domain, but gmail no longer allows you to send e-mails from your own domain name unless you provide your own SMTP server to send ...
4
votes
1answer
220 views

Postfix SMTP authenticated can send as anyone

The server correctly accepts/rejects the logins though dovecot's authentication mechanism, but after that I can pretend to be anyone when sending emails. smtpd_sender_login_maps = ...
1
vote
0answers
287 views

PHP mail() function - “from” name overwritten by Exchange Server

I originally posted this on stack overflow but was told it might be better placed here on Serverfault. I am trying to send a very simple email from a php script ...
2
votes
0answers
179 views

Does Google require TLS on port 587? Exchange 2010 SMTP has mail sent to GMAIL backed up in queue

Exchange 2010 SMTP has mail backed up in queue. Any email sent to Gmail sits in the queue while any email sent to another personal domain which has email filtering enabled errors, "asp.reflexion.net ...
0
votes
1answer
108 views

Limiting OpenVZ SMTP Per Hour

How would I limit SMTP connections per hour on the host node for a /24 block? For example, I want to limit it to 50 emails per hour. Thanks
0
votes
1answer
157 views

Postfix forward incoming emails to mailin

I've setup the smtp server using postfix with dovecot on mail.example.com server running on port 25. And then I've also setup another smtp server using mailin (http://mailin.io) on mail.example.com ...
0
votes
1answer
87 views

What is X-DKIM header for?

There are some emails with an X-DKIM header (next to DKIM-Signature) like this: X-DKIM: Sendmail DKIM Filter v2.8.2 DOMAIN SOMEVALUE However I am unable to find decent documentation for it. What is ...
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votes
1answer
128 views

Configure email SMTP Server on Apache2 [closed]

For a while we decided to use another Server (VServer "B") for our Mailserver. I transfered all email accounts and mailbox from VServer "A" to VServer "B". VServer "B" runs well and the clients are ...
0
votes
0answers
288 views

hMailServer SMTP installed in LAN, clients in LAN can send Email but clients from the Internet cannot

I had checked the troubleshooting guide and many posts here and could not find solution so far. I had setup a network in Azure Cloud with 2 VMs, 1 of which is domain controller and the other is Web ...
3
votes
1answer
216 views

SMTP errors with iOS devices

I'm trying to diagnose why when an iOS device like an iPhone or iPad is set up to use email with our server for the first time, these errors occur. We choose "Other" from the initial set of choices ...
0
votes
1answer
22 views

RFC5321 “receiver should check […] reply code” (why?)

In SMTP commands are sent by the sender and responses which all begin with a numeric code are sent by the receiver. but then there's this bit: RFC5321 sec4.2 Whenever possible, a receiver- SMTP ...
0
votes
1answer
201 views

Postfix: sendmail (php-cgi) with different IP as authenticated SMTP Users

my Postfix-Mail Server is delivering two main types of mails Mail recieved from php-cgi (sendmail), localhost relay Mail recieved from authenticated SASL SMTP Users Is it possible to define a ...
2
votes
1answer
752 views

postfix multiple IP SMTP banner

I've installed postfix 2.11.3 and we have multiple IP addresses on our server which we want to host two domains, isolated and running on their own IPs. domain1 unix - - n - - ...