Questions tagged [smtps]

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Send test mail using telnet via smtps (465) port

Based on this guide I am trying to send a test email using telnet from linux https://linuxconfig.org/send-an-email-using-telnet but the connection immediately disconnects: $ telnet smtp.gmail.com 465 ...
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Postfix encryption not available

EDIT #2 What's this error? Aug 17 02:27:19 mail postfix/smtpd[1197]: lost connection after CONNECT from unknown[x.x.x.x] Aug 17 02:27:19 mail postfix/smtpd[1197]: disconnect from unknown[x.x.x.x] Aug ...
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4 answers
2k views

Postfix smtp relay can send emails but not relay other hosts

Use Case: We have several Eaton PDU/PSUs that don't support SSL/TLS authentication. I was tasked with building a SMTP relay server that can take the basic SMTP/25 emails and forward them to our email ...
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1 vote
1 answer
2k views

How to set up DKIM using Let's Encrypt?

For long time I'm using Let's encrypt for all my encrypted services (HTTPS, IMAPS, SMTPS, FTPS). Now I want to add DKIM signature for my mail server. But is this possible using Let's Encrypt? I have ...
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  • 325
-1 votes
1 answer
240 views

How can i redirect smtp port 25 to port 465 [closed]

I have Exchnage server ,I can receive emails But I can not send emails out of the domain because Port 25 is block in ISP How can i redirect smtp port 25 to SMTPS port 465 ?
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2 votes
1 answer
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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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1 answer
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RFC for "Received: With ESMTPS"

Email Received: headers often say "With ESMTPS" but this phrase seems to have no standard describing it. is there an RFC for Protocol ESMTPS? RFC5321 only lists SMTP and ESMTP
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CentOS 7 - SMTPS on Postfix is not working right

First, I am a CentOS 7 newbie. I am running an email server on CentOS 7, I am currently having issue with setting SMTPS up on postfix. BTW, imap over SSL on port 993 is working fine. Port 465 and ...
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2 votes
1 answer
12k views

Postfix is not responding on port 465 (SMTPS) [closed]

I have Postfix and I've configured it to listen on port 465 for SMTPS. When I telnet to port 465, it does not respond but it does respond on port 25. I've googled for days and nothing has worked for ...
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1 vote
1 answer
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Minimum postfix config to send mails to a smtps server

I'm trying to send mails with python so I configured a postfix server locally. The python part seems to work as my mails reach the smtpd server. After that, postfix seems to correctly query the MX ...
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  • 341
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Self-signed certificate error with exim: CA is unknown

I added ssl support to my exim smtp server. Now I'm trying it with a Thunderbird client, first of all I imported my self signed certificate to thunderbird keystore and than I tried to connect. It ...
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37 votes
8 answers
5k views

Is enforcing encryption for SMTP a good idea (yet)?

I am running an email server which is currently set up to use TLS if possible, when sending and receiving emails. When you read in the documentation about this, there is also the option to enforce ...
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2 votes
2 answers
600 views

Postfix, carbon copy forwarded email

Basically this is the setup I am currently using: virtual_alias_maps x1 x2 recipient_bcc_maps x2 x3 When I send an e-mail to x1, I expect it to be forwarded to x2, and then copied to x3, but ...
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-1 votes
2 answers
2k views

Does Windows Azure blocks port 587?

I am trying to use Exim4 as my email server on Windows Azure. I found Exim4 uses STARTTLS to do SMTPS, and the port number is 587. The problem is I opened 587 in Azure vm Endpoints, but I can not use ...
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1 answer
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Connecting SMTP externally

I have got a local smtp server to relay to Google smtp so as to increase the limit of email recipient from 2,000 a day to 10,000 a day for specific users. I can send through this local smtp ...
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21 votes
3 answers
20k views

Postfix smtps and submission confusion

I've setup postfix so that email clients use port 465 (smtps) for outbound mail. I'm not really understanding the difference between smtps (port 465) and submission (port 587) What's the 'best ...
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2 votes
1 answer
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Howto enable SMPTS (465) postfix CentOS

I need help is enabling SMTPS. I use postfix , dovecot with MySQL(virtual domains). I do not know how to enable SMTPS(465). I already added tls related settings and key and certificate in the "/etc/...
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1 answer
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How much mail will be lost if I only support SMTPS?

If I configure my locally hosted SMTP server to only accept SMTPS connections (secure SMTP port 465/587), how much mail will I lose because sender(s) don't support sending on SMTPS? Are the major ...
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