Last month, NBC 7 Investigates teamed up with NBC stations across the country to test the speed of the world's largest mail service heading into the election.

We promised to keep testing the service, every month into November. And this week, we're doing just that. The big question is: If you mail your ballot, will it get to the elections office in time to count?

"We are watching,” said Bishop John Selders of Moral Monday CT, a postal service watchdog group. “We are paying attention. And so if there is some funny business, I think it will be observed."

Politicians are watching, too.

"I've never seen this -- this is my 14th year in the U.S. Senate,” said Sen. Bob Casey, D-Penn. “We've never had this many letters relating to mail delivery in such a short amount of time.”

"I've had no input from anybody at the White House,” insisted U.S. Postmaster General Louis DeJoy at a recent private event in D.C. “Nor would they have the authority to direct me."

And that settles it for DeJoy's defenders in Washington.

“I'm very confident that the vast majority will be counted,” Sen. Ron Johnson R-Wisc.

But NBC wanted to test that confidence.

So back in August, NBC 7 Investigates teamed up with NBC stations across the country, sending out more than 150 letters and keeping track of how long it took for them to arrive.
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This month, we mailed out even more letters - more than 400. And our results were nearly identical to last time:

• 88 percent of our letters got their destination within three days.
• 98 percent got there by the end of the week
• 2 percent arrived more than a week late
• 1 letter is still missing

If just 1 percent of the 1.9 million registered voters in San Diego County lost their ballots in the mail, more than 18,500 local ballots would go uncounted.

"Eighty-eight percent, 98 percent -- that's unacceptable,” said Eddie Cooper, president of the San Diego chapter of the American Postal Workers Union. “We want 100 percent."

"Here in San Diego, I'm feeling pretty confident,” Cooper added.

Cooper watches the news and while he concedes he has the same concerns as everyone else, he said as long as voters don’t all wait until election week to vote, there is no reason their votes won’t count.

"We are up to the task, up to the challenge, of delivering the mail-in ballots on time, with a sense of urgency, and we're ready," Cooper said. "We're ready."

All of the letters NBC 7 Investigates mailed to San Diego addresses arrived within one week, most within two business days.

NBC plans on doing another test in October.

A good reminder: In California, ballots must be postmarked by Nov. 3, which is Election Day, and received by Nov. 20 in order to count.