Does user need to keep updated with the certificates locally when using TLS with smtp?

HOWTO: Install/Configure msmtp and mutt on ubuntu

I got GTS CA 1O1 as the common name instead of Google Internet Authority G2. What is the difference between the two.

So GTS CA 1O1 refers to the one listed here https://pki.goog/?

I see GTS CA 1O1 valid until Dec 15, 2021. So by Dec 15, 2021, I should regenerate the local crt file by openssl x509 -inform DER -in GTS1O1.crt -outform PEM -out gmail-smtp.crt

$   msmtp --serverinfo --tls=on --tls-starttls=off --host=smtp.gmail.com SMTP server at smtp.gmail.com ([172.217.195.108]), port 465:     smtp.gmail.com ESMTP a10sm3703146oic.46 - gsmtp TLS session parameters:     (TLS1.3)-(ECDHE-X25519)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM) TLS certificate information:     Owner:         Common Name: smtp.gmail.com         Organization: Google LLC         Locality: Mountain View         State or Province: California         Country: US     Issuer:         Common Name: GTS CA 1O1         Organization: Google Trust Services         Country: US     Validity:         Activation time: Tue Nov  5 15:45:23 2019         Expiration time: Tue Jan 28 15:45:23 2020     Fingerprints:         SHA256: 50:E7:13:03:7B:A8:D8:28:3C:D2:66:AC:58:E3:76:6D:BB:DB:E2:9D:B6:8F:54:38:10:BC:A5:93:67:25:7D:4D         SHA1 (deprecated): F4:D9:49:8F:FA:F0:06:D1:B8:D7:AE:A8:56:A3:36:B4:FB:76:3E:32 Capabilities:     SIZE 35882577:         Maximum message size is 35882577 bytes = 34.22 MiB     PIPELINING:         Support for command grouping for faster transmission     AUTH:         Supported authentication methods:         PLAIN LOGIN OAUTHBEARER  

Need help with enable TLS in Postfix for SMTP Relay connector to Office365

Need help with enable TLS in Postfix for SMTP Relay connector to Office365

I am new to TLS.

I`ve successfully configured my Postfix SMTP Relay to relay emails to my internal Application by using office365 connector on 25 port.

Due to Security concerns need to relay SMTP to port 587 TLS.

PLS any one help me to how to configure TLS in Postfix SMTP Relay from scratch?

WP Mail SMTP: What do the SSL/TLS options mean?

When setting up the WPForms WP Mail SMTP plugin, I got this choice:

screenshot

Encryption: ( ) None ( ) SSL ( ) TLS
For most servers TLS is the recommended option. If your SMTP provider offers both SSL and TLS options, we recommend using TLS.

What do those options mean? Do they mean (like in normal conversation):

  • SSL = SSLv3
  • TLS = at least TLS 1.0

or do they mean (like in Outlook and some other mail clients):

  • SSL = TLS
  • TLS = STARTTLS

I was assuming the latter, because that is really common with mail stuff.

But if that is the case, why would the plugin recommend to prefer “TLS” (STARTTLS, which is insecure) to “SSL” (TLS, which is safe)?

How does a spammer typically setup smtp infrastructure? [on hold]

I am a bit confused when it comes to spammers sending spam from botnets. I know that protection mechanisms like SPF and DKIM are there to validate the mail through ip whitelisting and cryptographic signing. But how would a spammer send a huge amount of emails if he was spoofing a domain without SPF and DKIM? Because even if he had many bots, he would have to use a third party provider like gmail or yahoo, because they do have FQDN’s. And an attacker would not use gmail or something similar since it would easily be detected and it would probably not allow host spoofing.

So, is a FQDN needed to deliver spam emails or do botnets set up their own local smtp server on each bot and send from there? Won’t this traffic be blocked somewhere? It is just not clear to me, how a spammer would typically set up the smtp server structure. How are these spam floods possible?

Enviar fixeiros de texto pelo smtp em python

Exixte alguma forma de enviar fixeiros .txt pelo smtplib do python?

Este é o meu codigo atual:

    server = smtplib.SMTP('smtp.gmail.com:587')     server.starttls()     server.login(Sender, Password_SMTP)     server.ehlo()     body = 'Bump request was successful.'     subject = 'Bump request was successful'      message = 'Subject: {}\n\n{}'.format(subject, body)      server.sendmail(Sender, Reciever, message)     server.quit() 

Check SMTP connection in health check

I have created a web service which can also send emails (using Gmail SMTP). This is deployed using Kubernetes and a health check is run every 30 seconds.

Since a team member changed the login credentials we use for sending emails, a check for the SMTP connection has been added as part of the health check. Now the health check tends to fail with the following error:

Invalid login: 454 4.7.0 Too many login attempts, please try again later. - gsmtp 

Should verifying the SMTP connection be part a health check? Or would it be better to just skip this check? Most of the system can still function properly without using SMTP.

Suspicious SMTP server client activity – non-ASCII queries

I’ve noticed some strange activities from some remote host connected to our SMTP mail server. Queries contains non-ASCII characters, below is the copy of one of them (to each query our server responded with “command not implemented”):

..._)....pz4.H.T7.&...4..rШ./.+.... ..

The hex representation is:

20 00 00 00 5F 29 00 00 00 00 70 7A 34 00 48 00 54 37 00 26 00 00 00 34 00 00 72 D8 00 2F 00 2B 00 00 00 00 20 20 20 20 00 00 

What is the goal of such queries? Is this some kind of security attack / searching for “black doors” or something?