GMAIL SMTP settings - Sign-in attempt prevented message

Hi all,

I configured my SMTP settings yesterday before a cook over night. Unfortunately, it ended up cooking a little longer than expected because both my e-mail notification and app notification failed. However, I got an e-mail from gmail saying that it prevented a login to my account at the time when the alarm probably went off -
When I try to review the devices it doesn't show on there.


Hi Jerry,
Someone just tried to sign in to your Google Account XXXX@gmail.com from an app that doesn't meet modern security standards.

We strongly recommend that you use a secure app, like Gmail, to access your account. All apps made by Google meet these security standards. Using a less secure app, on the other hand, could leave your account vulnerable. Learn more.


This is how I have my stmp setup:

Server - smtp.gmail.com
Server port number - 465
Email 'from' address
xxxx@gmail.com
Requires authentication box checked off
Account user name - xxxx@gmail.com
Account password - my password
Enable TLS/SSL encryption checked off
Use STARTTLS box unchecked
Verify server certicate box unchecked

EDIT - I just discovered a setting under security in gmail to allow for "unsecure apps" to access gmail. Is this what I need to change? Also, what is a good way to run a test e-mail through the heatermeter? Trying to figure out how to send one without it going through an actual alarm.

EDIT2 - okay, figured out why the test e-mails weren't going out as I was using a different probe and I didn't "save" the changes to notify via e-mail and sms when I was hitting the "test" button.

So, just want to confirm about the security settings and if that is okay to change that to less secure and if there is any way around it. Would suggest maybe adding that to the FAQ/guide too for gmail users. Maybe I will just use a separate "heatermeter" gmail account.

Change your port to from 465 to 587 and enable STARTTLS.

From: https://support.google.com/a/answer/176600?hl=en

Port 465 (SSL required)
Port 587 (TLS required)

Steve_M said:

Change your port to from 465 to 587 and enable STARTTLS.

From: https://support.google.com/a/answer/176600?hl=en

Port 465 (SSL required)
Port 587 (TLS required)

Click to expand...

Thanks, will try that.

JerryF said:

EDIT - I just discovered a setting under security in gmail to allow for "unsecure apps" to access gmail. Is this what I need to change? Also, what is a good way to run a test e-mail through the heatermeter? Trying to figure out how to send one without it going through an actual alarm.

Click to expand...

Looks like you have to enable this now. I just ran into the same problem while running through some checks.

Since this is the case, I would also suggest creating a separate gmail account just for sending HM alert messages. This way you are effectively air gapped from an account breach, unless you're using the same password, which is also bad!

Yeah if you have two factor authentication turned on in GMail it gives you the error telling you you need to generate an app password.
If you have two factor off and allow less secure turned off you get this error

It would be cool if they said what "up to date security standard" they are referring to. For funsies I edited the source code of the MSTMP application and forced it to negotiate an TLSv1.2 connection (the latest standard) with DHE-RSA-AES256-GCM-SHA384 (a relatively recent high-security cipher) and it negotiated successfully. However, when I attempted the AUTH PLAIN, I still got the same response about logging in via a web browser. I see that once this session is established the server says it supports the auth mechanisms: LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH. I tried login and plain and both failed the same way. The other three are OAuth mechanisms which I am guessing is the only way they really accept now.

I know what your problem is--check my posting of a few minutes ago.