By Leslie Ye,

Business emails: Easy to send, difficult to perfect.

Professionals receive an average of 88 business-related emails a day, according to the Radicati Group’s 2015 Email Statistics Report. So how are you supposed to stand out?

Answer: your subject line. Short (40% of all emails are opened on mobile first, where only four to seven words are visible) and to the point, they either act as a tantalizing teaser or a reason to send your email straight to the trash folder.

Just because you’ve already gotten your prospect to open and respond to your first email doesn’t mean you’re guaranteed to keep the conversation going. What happens if your contact goes silent? You can’t exactly send a “Coming in ice-cold, but hoping to help” email for a second time.

Below are 16 email subject lines you can use to restart a stalled conversation without getting lost in the noise.

1) “Closing the loop”

The header of Blair Enns' trusty breakup email, this subject line isn’t attached to a big ask or even a small one. It just states a fact -- you’re wrapping the relationship professionally, unless your prospect tells you not to.

2) “Re: ”

Instead of counting on the fact that your prospect remembers your name and what you were talking about, build your previous interactions right into your subject line when attempting to re-engage by replying to your last email. According to a ContactMonkey study, sales emails with “Re:” as the subject line are opened 92% of the time.

3) “Should I stay or should I go?”

A straightforward question + a pop culture reference = gold.

4) “Here’s that [resource] you were looking for”

If your prospect requested specific resources and then never responded, follow up with a new tidbit of information to keep them interested.

5) “Persistence or harassment?”

A little self-awareness goes a long way. Even if you don’t intend to bother your prospect, their threshold for annoyance might just be low -- simply acknowledging this can get you back in their good graces.

6) “Am I off base?”

This subject line invites your prospect to redirect your conversation toward a topic that’s useful for them ... or end your relationship altogether. Either way, you get closure.

7) “Are you seeing someone else?”

Has your prospect gone with a competitor and just hasn’t bothered to tell you? Give them an off ramp so you can restart the deal or mark it closed-lost. (Note of caution: Use only if your prospect appreciates cheekiness.)

8) “Still on track for [goal]?”

Creating a sense of urgency is always helpful for spurring action. Provided you’ve had a conversation about their goals before, remind your prospect of the reason they were speaking to you in the first place.

9) “Only X weeks left to achieve [goal]”

A more urgent version of the above, use this subject line if you also discussed a timeline accompanying their goals. There’s nothing like an impending deadline to get prospects moving.

10) “This will only take 26 seconds”

As a rule of thumb, the shorter the email, the better -- your prospects are busy people. Show them you’re aware their time is valuable by outlining exactly how long it will take them to read your email. Keep the ask simple so they can respond quickly as well.

11) “Any questions, ?”

People love the sound (or the look) of their own name. Get their attention by including their name in your subject line, and then ask how you can help.

12) “The ball’s in your court”

Another breakup email subject line, this one lets your prospect know right off the bat that your relationship is in their hands.

13) “?”

This subject line is simply intriguing -- what do you want? To find out, your prospect will have to click.

14) “Some thoughts on [problem]”

Even if your prospect isn’t ready to buy right now, help with their business pain will always be welcome. Sometimes offering your insights is enough to keep the conversation going.

15) “?”

A spin on #11, this subject line is short, sweet, and to the point. Where is your prospect? Hopefully they’ll tell you.

16) “ :( ”

If a picture is worth 1,000 words, how much is an emoji? Definitely at least one email click. (Again, only use if you’re in an industry that’s comfortable with a little informality.)