Email etiquette isn't easy. As the summer draws to a close, your work inbox will likely be populated with those dreaded, out-of-office replies. Or, more likely, you may have to write one yourself.

Entrepreneurs and business leaders know well that email etiquette can be quite challenging; it's important to be concise, but not vague. On topic, but never pushy. Smiley faces and emojis are verboten -- at least in most cases -- and exclamation marks, if necessary, should be kept to a minimum. 

Lindsey Pollak, a millennial workplace expert and author of "Becoming the Boss: New Rules for the Next Generation of Leaders," is an expert in this field. Ahead of your next extended vacation, or few days out of the office, she provides a few pointers for communicating your absense to the world:

1. Only include relevant information

The point of an out-of-office message is to let your colleagues and contacts know that you'll be out of pocket.  

Pollak says there are two essential things to include in your message: Let them know when they may expect to receive a response, and, if possible, who they can contact in your abense if it's a matter of urgency. 

2. Don't be afraid to add some (reasonable) flair

Once the relevant information is there, it's fair to get a little personal with your text. "When someone does incorporate some humor and get creative -- the right way -- I appreciate the effort," says Pollak.

She shares one of personal favorite messages: "Gone sailing, will respond to messages on Monday." 

The text is short and sweet, but also gives readers a small window into that person's life and interests outside of work.  

3. Be positive.

Projecting a positive attitude has a significant impact on others and on the workplace, as a 2007 Wharton study finds. A few kind words won't hurt. If anything, it'll help -- especially if you receive an email from an important investor or potential client while you're gone.

Pollak recalls an auto-response that instructed recipients to follow up with her "wonderful and capable assistant."

That, she says, not only reflects well on the assistant, whom readers now know that they can trust, but it also lets them know that the writer is generally good-spirited, and is willing to give credit where credit is due. (This can only bode well for your relationship with the sender upon your return.) 

4. Know your audience

"Out-of-office messages, can be dicey," says Pollak. You certainly don't want to be tonally inappropriate with an email that tries (and fails) to be witty. You end up taking the risk of driving important contacts away.

While certain industries can get away with a little humor (creative agencies, for instance, might typically be more liberal with banter), it's still worth considering how a message comes off to your colleagues or partners in other industries.

The trick, she says, is to know your audience; you can't always communicate in the way that feels right to you specifically.

Ultimately: "If there's doubt, don't." 

5. Know your position

If you're a senior executive at a high-profile company, odds are that an automated email message won't have any great bearing on your livelihood. "Mark Zuckerberg, for example, can write whatever he wants," Pollak quips.

Still, for those of you not-yet cemented at the world’s next Facebook or Uber, consider toning down the fanfare -- or at least saving it for an in-person meeting.