Gmail prevents access through Secure Line?

[Shepard]

I use a 3rd party program that logs in to a gmail account and downloads files attached to emails.  When Secure Line is active Google denies login and sends me a text notifying of unauthorized access attempts.  If I disconnect Secure Line, all works fine.

[Shepard]

OK - Figured this out for anyone else that encounters this.  The way I got this to work is to use a normal browser (I used Firefox) go to the gmail account in question that was preventing access through Secure Line.  Google will also prevent access this way too but will give you options to verify your identity.  I used the "send code to cell phone" method, entered the code, and then access through Secure Line works.

[schmidthouse]

OK - Figured this out for anyone else that encounters this.  The way I got this to work is to use a normal browser (I used Firefox) go to the gmail account in question that was preventing access through Secure Line.  Google will also prevent access this way too but will give you options to verify your identity.  I used the "send code to cell phone" method, entered the code, and then access through Secure Line works.

That is correct. When the email client tries to access web base email accounts and you're connect to Secureling the IP address won't be recognized and will deny connection as you experienced.
If you then go online and directly sign in while connected to Secureline then it also can resolve itself.
It's a security layer by web based email accounts to deny unrecognized sign in perimeters.
The receiving of a notice and "send code" options will also ocurr.