Questions tagged [starttls]

STARTTLS is the SMTP command to connect to email servers securely over TLS (formerly SSL). Use with an email server tag like [postfix], [exchange], etc.

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sendmail does not issue STARTTLS when acting as a client

I'm having problems relaying to servers that whise mail is routed through mimecast. Connections are being rejected with the message: 553 This route requires encryption (TLS) - https://community....
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Mail server sending to postfix refusing TLS connection with "certificate expired", but it's not

Since April 30, I'm seeing errors like that in my mail log: May 1 02:27:27 afaron postfix/smtpd[2644268]: connect from r137.info.hofer.at[66.117.17.137] May 1 02:27:27 afaron postfix/smtpd[2644268]: ...
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Personal OpenSMTPd relay fails when using "tls-require", works fine with just "tls"

I'm currently setting up a somewhat unique personal email server using OpenSMTPd. I have a local server (Raspberry Pi) and a remote server (VPS). Emails sent to me are sent to the remote server and ...
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Cannot get Mutt/Gmail/OAuth2 to work - cannot STARTTLS

I'm trying to get Mutt working with Gmail using OAuth2. I'm using Debian 10 and have compiled Mutt 2.2.1 with --enable-smtp. I've created my tokens. My muttrc contains: set smtp_oauth_refresh_command=&...
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Can't configure SMTP encryption - postfix

I have docker-mailserver and Roundcube in containers, beside there is MySQL database for mail data and user passwords. Dovecot inside is configured to verify logging in users passwords with database. ...
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tls negotiation failed the certificate doesn't match the host

I'm tryin to setup Gmail send-as to send email via my SMTP server over TLS and I get "tls negotiation failed the certificate doesn't match the host" ever since I renewed my lets encrypt cert....
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Postfix is getting "TLS Is required, but was not offered by host"

I've searched every forum, every article, every serverfault.com post for this issue. I'm using a fresh setup of Postfix. It is managed by Virtualmin. Whenever I try to send mail via TLS, I get the ...
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TLS/SSL on http (80) with STARTTLS

I'm researching the reason why TLS/SSL is not using over HTTP. Other protocols, such as SMTP, POP3, FTP, etc can be used on SSL ports (SMTPS, POP3S, FTPS) for the first way, and the second way is to ...
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does SSL/TLS STARTLS full encrypt connexion for POP and IMAP

I am configuring POP and IMAP accounts in thunderbird mail client. Here are 2 options: Security: None SSL/TLS STARTLS Authentication method: Normal password Encrypted password Kerberos / GSSAPI ...
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Using stunnel as proxy between SSL versions for SMTP with STARTTLS

I have a quite old software which doesn't support TLS 1.2. However SMTP Server only supports TLS 1.2. Now I wanted to use stunnel to connect to SMTP server and and also listening for smtp access. I ...
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Why is port 587 preferred over port 465 in SMTP?

I have recently been developing a C# client which sends emails via a SMTP server. However I have been as to what the different terms ment, like: STARTTLS/TLS/SSL... I had a faint idea of what they ...
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Gmail failing to accept TLS

I recently set up a postfix mail server. Testing it with other domains, everything seems to work well. However, when my server tries to send messages to gmail, they are marked as spam, with the red ...
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Are SMTPS and IMAPS ports really deprecated?

I've read that STARTTLS command was added and intended to deprecate the SSL ports. But even major mail servers like google still use SSL ports and even don't allow us to use classic ports with ...
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How to read an OpenSSL cipher suite list

hMailserver is an open source Window e-mail server. For incoming e-mail it supports STARTTLS with the help of OpenSSL 1.1.1. It allows configuring the cipher suites, the default is: ECDHE-RSA-AES128-...
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Postfix 3.3.1 on Centos 8 can't enable TLSv1 or TLSv1.1

I recently migrated my main mail server to a new one, the old one had been running for almost 10 years and was the production server for around 20 domains and over 40 mailboxes. Everything went well ...
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Getting postfix to relay SMTP/SSL/TLS to Charter/Spectrum

I'm running Postfix on Debian as an MX for a small LAN and trying to get SMTPS working with mobile.charter.net over port 587. I followed a few links off google for setting this up along with a post on ...
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NSS-LDAP not working over TLS: do_open: do_start_tls failed:stat=-1

I'm using NSS-LDAP for authentication. Without TLS, everything works fine. Once I enable TLS (StartTLS) with a self-signed certificate, which I have added to the client, NSS-LDAP won't connect to the ...
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Outlook 2010 can receive but not send - authentication fails - Thunderbird works

After the mailserver was upgraded from CentOS6 to CentOS 7, Outlook 2010 on Windows 7 can receive email but not send, the error says authentication failed. However Mozilla Thunderbird can receive and ...
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Deny non TLS incoming mail with postfix and force certificate check

I want to deny non TLS incoming mails on my postfix server. Here is what i've done: smtpd_tls_security_level = encrypt smtpd_tls_auth_only = yes I do not really understand the difference between ...
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Will msmtp fallback to unencrypted connections if encrypted connections fail?

My ~/.msmtprc config file says to connect to a server on port 25 with tls on and tls_starttls on. Is there a risk that, if the encrypted connection setup fails for some reason, then msmtp will ...
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Postfix 3.4.9 SSL issues -- no shared cipher from servers using TLSv1

Edit 1: I've narrowed it down to TLSv1 that both servers listed below (no others have failed yet) are attempting to use. I'll be contacting their webmasters requesting they stop using an insecure ...
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Apache and TLS mode - password in plain text in wireshark

My apache.config: LDAPTrustedMode TLS LDAPTrustedGlobalCert CERT_BASE64 /etc/pki/tls/certs/ca.cer AllowOverride None Options None #Order allow,deny #Allow from ...
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TLS from unknown: No client certificate presented

We have setup a windows server virtual SMTP (under IIS6 manager). In the SMTP settings, TLS encryption is enabled, fqdn field is "sharepoint.mycompany.com". In the server's cert store "personal" ...
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CentOS OpenLDAP STARTTLS wierdness

I am having a very strange problem configuring my CentOS OpenLDAP for STARTTLS. Here's what's going on. I have a bunch os scripts that I use to configure my system. I do this to document a machine's ...
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2 votes
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Do any reputable mail servers require STARTTLS encryption for SMTP delivery?

Are there any large, reputable MTAs (like gmail, hotmail, icloud, etc) that will bounce mail or otherwise fail to deliver if the receiving MTA doesn't support STARTTLS? Put another way, will ...
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Postfix bounce when unable to validate TLS option

I'm using postfix as mail transfer agent on my mailgateway to send and receive emails. Because I'm communicating with sensitive information I'm using the tls options to validate the receivers mx. He ...
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Server 2012 R2 SMTP service not sending mail to non TLS servers

We have SMTP virtual server on server 2012 R2 server. I have configured it to use TLS connection. We do have real sertificate etc. Everything works fine except mail that is going to mail server which ...
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Ambari sync with LDAP using StartTLS

I'm facing an issue to sync Ambari with a LDAP server using StartTLS and a self-signed certificate. Ambari server and ldap server are both running on the same machine. I've followed the steps written ...
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No STARTTLS with Dovecot and Postfix

I have done a lot of searching and am not finding a solution. I had to reload Mageia 6 on my email server. I am using dovecot-2.2.34-1.mga6 and postfix-3.1.6-1.mga6. Openssl is openssl-1.0.2o-1....
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I'm able send email via Thunderbird, but not via my own app. The email settings are identical

I have my Postfix server. I can send email via it with no problem using Thunderbird. For smtp I have: port - 587 Normal Password STARTTLS However, I can't send an email through the same server via ...
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Trying to make submission (587) work - Exchange 2016

I'm trying to allow the authenticated relay (Client Frontend connector) to process requests from LAN and internet, but I'm struggling so far. First, I have linked this connector to my SSL wildcard ...
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Client did not present a certificate (Postfix)

I have postfix SMTP relay which have been configured with TLS option. Now just realized when sending email to gmail (for example) using Microsoft outlook,found out this "Client did not present a ...
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Postfix STARTTLS encryption before authentication

I'm trying my best to configure Postfix with STARTTLS using port 25. Now the problem is STARTTLS is not working on port 25. 250-VRFY 250-ETRN 250-XXXXXXXA 250-AUTH PLAIN LOGIN 250-...
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Mail server: Does /etc/mailname have to match SSL certificate CN?

I set up a web and email server on a VPS that uses apache2 with multiple virtual hosts and postfix, dovecot, and roundcube for the email server. I am getting an authentication failure when trying to ...
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postfix tls not reading or finding key

I've been having issues sending mail to my server, and there are indications of TLS errors (mostly from the maillog). What I've tried: Ensuring that postfix / dovecot can read the certificates (made ...
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3 votes
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Sendmail process crashes as soon as STARTTLS is received

I just upgraded my server from FreeBSD 10.3 to 11.1. It's now running Sendmail 8.15.2 and OpenSSL 1.0.2k-freebsd 26 Jan 2017. Since the upgrade, sending mail to my server is failing. I cranked up ...
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Is TLS necessary for port 25 for MX delivery?

I am in the process of implementing a new Postfix implementation on an existing environment which is extremely old. While doing so I am requiring all clients to connect securely on either 465 or 587 ...
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SMTP Server (Exchange 2003) hangs up on client after STARTTLS command after adding cert

I am stumped on this. I have Exchange Server 2003 still in use. I created a valid LetsEncrypt SSL cert, and successfully imported the pfx in my Default SMTP Virtual Server properties, Access tab. ...
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Does DNS need to be pointed toward the right sever, for SSL to work

So the issue I'm having, is with a new mail server I've been setting up. Now it seems to work fine when not using ssl. And if I try using ssl, with a mail client like airmail it says host name ...
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7 votes
2 answers
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How can I decrypt STARTTLS communication over SMTP in a packet capture (if I have the private key)?

For the purpose of troubleshooting, I need to see what an email looks like when it's sent to my sendmail server via SMTP. The upstream server requires the SMTP connection to use STARTTLS so a packet ...
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5 votes
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SNI like equivalent for starttls

I am trying to host two seperate domains on one IP address. I want to be able to determine from the STARTTLS command which certificate was being requested and forward to a different mail server based ...
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2 votes
1 answer
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Disabling SSLv2 in Courier IMAP

I'm attempting to disable SSLv2 support (amongst other things) in Courier on Linux. In /etc/courier/imapd-ssl I have: TLS_CIPHER_LIST="HIGH:!MEDIUM:!SSLv2:!LOW:!EXP:!aNULL:!ADH:@STRENGTH:!3DES" ...
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Can't connect to Exchange 2016 with port 587 TLS

Hi everyone i'm having issues with SMTP notifications connecting on port 587 with TLS. Right now I have an internal Exchange 2016 server and all email works great. I have a few customers who have ...
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2 votes
1 answer
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Postfix TLS encryption: smtp_* vs smptd_*

I am really confused about the postfix TLS settings. There are in each case settings for private keys and public keys. smtpd_tls_cert_file = smtpd_tls_key_file = smtpd_* And smtp_tls_cert_file = ...
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Configure OpenLDAP using GnuTLS with TLS=required

We have an openldap server and don't want to allow unencrypted communication, so acceptable is either tls over port 389 (starttls) or ssl over 636 (ldaps). As we use slapd.conf for configuration, ...
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1 vote
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Postfix TLS Roundcube problems

im writing this because i have a problem when i try to test SMTP with Roundcube. Before i had no problem with Postfix ou Dovecot. It seems like it's a TLS problem : SMTP Test When i look in my log ...
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How to force postfix to deny all non TLS queries?

I have a server with postfix and a plain text authentication. It accepts both TLS and non-TLS authentication. How can I force the server to deny all non TLS queries so that the mail users never send ...
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9 votes
3 answers
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Postfix configure to use TLSv1.2

I start build my first cloud server: Ubuntu 16.04 with postfix. Question is how can i configure postfix to use TLSv1.2 when i send mail from my webshop? When my webshop sending mail to my postfix ...
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Unable to send email from Command Line in Postfix (warning: TLS library .....)

I configured postfix with ssl/tls. and created an smtp. However I am unable to send test email and/or login. "Text below first defines error log (different attempts) and then configuration files." ...
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Does anything changes for a client in the API communication after the command STARTTLS is sent and a response received

I'm trying to understand how the command STARTTLS in IMAP works exactly and what becomes different when it's sent. After I've sent the command "STARTTLS" before login process and received the response ...
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