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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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How can I explicitly disable TLS when sending to one specific recipient?

I have a SendMail 8.14 server deployed in the middle of an SMTP workflow (Outbound mail looks like Exchange -> SendMail -> Appliance -> Internet) I have TLS configured for the first three hosts. This works fine for the most part but I need to…
Mike B
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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 certificate" on the recipient's mail header Received:…
David 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-ENHANCEDSTATUSCODES 250-8BITMIME 250 DSN AUTH LOGIN 334…
David A
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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 the log level to show all incoming and outgoing…
FKEinternet
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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" TLS_PROTOCOL=TLS1 TLS_STARTTLS_PROTOCOL=TLS1 This…
Ian480
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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 = smtp_tls_key_file = smtp_* What is their…
cytopia
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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, olcSecurity isn't an option. TLSCipherSuite seems to…
blockbax
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Postfix STARTTLS works in LAN but not externally

if I connect in LAN on port 25 to my mail server, it offers STARTTLS telnet mailserver.com 25 Trying 192.168.0.x... Connected to mailserver.com Escape character is '^]'. 220 mailserver.com ESMTP Postfix ehlo…
Florian
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How to disable SSLv3 in Postfix 2.11?

I just noticed (by some online check tools) that my mailserver may allow SSLv3 and updated my configuration. My current config in Postfix 2.11.2: # inbound smtpd_tls_security_level = may smtpd_tls_mandatory_protocols = !SSLv2 !SSLv3 #…
burnersk
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Postfix still complains that "certificate verification failed" even when "smtp_tls_security_level = fingerprint"

I'm attempting to use Postfix (version 2.6.6 on RHEL6) to connect to and send mail via a mail relay on our internal network. I want to connect with STARTTLS on port 25 (port 465 is not available on this server). The mail relay uses a self-signed…
fronzee
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How do I log tls-encrypted smtp traffic?

I'd like to know what my local postfix says to the Amazon SES smtpd after the STARTTLS. In plain text, so I can understand it. Amazon SES requires TLS, so I can't temporarily turn it off. I currently log both legs of the traffic with this…
Johannes Ernst
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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 ment out of context, but email wise i had no…
Choppa dude
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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 setup and to ensure that I set it up the same way…
Mister Rose
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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 reputable MTAs generally retry delivery without TLS if an…
ATLief
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ssmtp settings for namecheap: Invalid response SMTP Server (STARTTLS)

I am trying to configure ssmtp to use the namecheap smtp server to send emails. My current…
Sgoettschkes
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