The man with the “best words” doesn’t have the best email marketing tactics, it seems.

After news broke that Hillary Clinton’s campaign had $42 million in the bank while Donald Trump’s campaign had a small $1.3 million as of May 31, Trump sent his first fundraising email.

On June 21, supporters on Trump’s mailing list received an email with the subject line, “The First One.” Well, they were supposed to.

According to Ad Age, nearly 60 percent (59.3 percent, if you want to get specific) of those emails went straight to spam folders. Only 12 percent of recipients opened the email and 6 percent of recipients deleted it without reading.

These numbers come from Return Path, an email data solutions provider that uses its consumer panel of 2.5 million people to measure how marketing campaigns are doing in public.

Another number worthy of highlighting: $3 million. That’s around how much the Trump campaign claimed the online efforts brought in on the first day.

Do note: It wasn’t all from the email. “The campaign raised $3.3 million on Tuesday and $3.4 million yesterday,” Trump spokeswoman Hope Hicks told Ad Age. “Only a portion of that was via email marketing and the remainder is attributed to online donations.”

And if we add in the “up to $2 million” the billionaire offered to match in the email, that’s more than $5 million.

OK, $5 million in one day is nothing to sneeze at. (Providing you believe the campaign actually brought in that much money. Many do not, especially considering Trump’s paltry fundraising totals thus far.)

But with such basic, fundamental email marketing errors at play, think how much money Trump’s campaign left on the table by not employing best and basic practices.

Whether you trust his numbers or not, we always can benefit from a solid reminder of why we need to execute the fundamentals of email marketing. Here are three basic lessons we can take away from this spam-worthy snafu:

1. Don’t use an unknown domain name.

The average monthly spam rate for email in 2015 was 7.03 percent. Yet, this email nabbed a whopping 60 percent. How did this happen? It could have a lot to do with where the email came from.

Previously, the Trump campaign sent emails from DonaldTrump.com, Ad Age reported. But on June 16, just days before this email was sent, it began to send emails from DonaldJTrump.com.

It seems like common sense: Stick with what works. Make sure when your organization makes an ask you already have established contact with the recipient from that same domain. An unrecognized domain is a chief way to land squarely in the spam folder.

2. Test, test, test.

Organizations are on constant searches for the next best way to target and reach their audiences. One of the primary ways of doing this is through constant A/B testing. This doesn’t seem to be a concern of the Trump campaign.

“According to Return Path’s data, we see no evidence that the Trump campaign did any testing or segmentation with his email campaign, ‘The First One,’” said Tom Sather, Return Path’s senior director of research.

According to Return Path, in May, the Trump campaign delivered 21 targeted emails, 7.9 percent of which went into spam filters. By comparison, the Bernie Sanders campaign sent 272 targeted emails, with a 0.3 percent rate, and the Clinton campaign sent 658 targeted emails, none of which were marked as spam.

Better targeting efforts not only boost chances that the email will resonate with the recipient, but also better the chances that it’ll get to the individual in the first place.

3. Harness the power of the subject line.

“The First One.” That was the unbelievably vague subject line for this particular fundraising email. (The first one what? The first one to break through the spam filter? No, that's not it.)

The subject line is the recipient’s first impression of the email. And this one doesn’t provide any information, let alone a call-to-action or an emotional sentiment—staples of successful subject lines. Statistics showed the odds were stacked against Trump's fundraising email. Thirty-five percent of email recipients open email based on subject line alone, and 69 percent of email recipients report email as spam based solely on the subject line.

Be sure to make your subject lines grab the recipient’s attention and establish a connection amid dozens of other emails in his or her inbox. Need a place to start? Try out CoSchedule's nine best practices for email subject lines.