Please tell up; What link(s) you are using? What you were doing? What if any error messages?

I am not using a link. I am typing www.usps.com in directly. I had been doing this frequently for years until approximately 3 months ago when it stopped allowing me to do so. Below is the message I always receive now. I did not make any changes to my computer system. Thank you for any assistance you can give me. Access Denied You don't have permission to access "http://www.usps.com/" on this server.

Reference #18.3da75b68.1453991824.ad94b90

This message is generated by a filter protecting the server. It seems to be a service/device used by many sites. The filter may be reacting to something unusual about your connection, but in other threads involving other sites, users reported it cleared up by itself after a few hours, perhaps indicating that a range of addresses was blocked temporarily to stop an attack and it also affected innocent users.

Oh, 3 months! Well, in that case, your request might be routed through a network the filter considers suspicious, or it may have been missing normal data (cookies, user agent, referring site, etc.).

You could start by checking for any modified connection settings here:

"3-bar" menu button (or Tools menu) > Options

In the left column, click Advanced, then above the page on the right, Network, then the "Settings" button.

The default of "Use system proxy settings" should piggyback on your Windows/IE "LAN" settings, but you also could try "No proxy".

If you think there could be a malware issue, try:

(1) Firefox's Safe Mode, to deactivate extensions to help you assess whether these are causing the problem. Judging from your screenshot, that will change the appearance significantly, but you can probably find your way around enough to conduct the test.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement? (More info: Diagnose Firefox issues using Troubleshoot Mode)

(2) Scan for and clean up unwanted software. See: Troubleshoot Firefox issues caused by malware.

Any progress so far?

Since the HTTP address redirects to the HTTPS address, does it make any difference if you use that directly:

https://www.usps.com/

As suggested, I typed in https://www.usps.com and it still failed

I also tried changing from "Use system proxy settings" to "No Proxy" and it still failed.

Bug 1242306 - Users unable to login to Macy's; Access Denied: You don't have permission https://bugzilla.mozilla.org/show_bug.cgi?id=1242306 Either of these makes Macy work: network.http.spdy.enabled = false network.http.spdy.enabled.v3-1 = false

This is fixed in v44.

Type about:config<enter> in the address bar. If a warning screen comes up, press the Be Careful button. At the top of the screen is a search bar.

I did what you suggested and I do see the Search bar, but I have no idea how to proceed.

Hi Frustrated11111, this is a more step-by-step explanation of Fred's suggestion:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste spdy and pause while the list is filtered

(3) Double-click the network.http.spdy.enabled preference to switch it from true to false and see whether that makes any difference.

Or if this is correct:

FredMcD said

This is fixed in v44.

You could try updating to Firefox 44. Please see: Update Firefox to the latest release.