If you're looking for a new job, no matter the type or level, you're likely to be sending your credentials to recruiters or employers by e-mail. But online job-search correspondence often presents a conundrum to job seekers. Their qualms can range from whether to include a cover letter to what to put in it.

When Ron Melnik set about contacting prospective employers and recruiters during a job search last fall, the Connecticut financial executive chose an approach that he thought would be effective with busy managers like himself. First, he identified a specific individual at a firm and called him or her to briefly introduce himself, then usually followed up by e-mailing a short cover letter and an attached resume.

His cover letter was an abbreviated version of a letter he'd have sent through the regular mail. It described his experience and interest in two concise paragraphs.

The approach resulted in a speedy and productive search. In six weeks, Mr. Melnik fielded several job offers and accepted a position as chief financial officer of Plastic Design Inc., a Middletown, Conn., custom injection molding company.

E-mail boosts the efficiency of the traditionally lengthy and time-consuming job-search process, but it can present new challenges, along with opportunities to make costly errors. To ensure e-mail helps, instead of hinders, your job search, apply the following tips:

Always include a cover letter. Recruiters and hiring managers often use cover letters as a way to determine their interest in a candidate. "I don't want to be forced to open the attachment to find out if I have any interest in this candidate," says Randy Block, president of Block & Associates, an executive recruiting firm in Larkspur, Calif. "Since I get dozens of e-mails a day, in most cases I won't take the time to open the resume if the cover letter doesn't tell me something valuable about the candidate."

Keep it short. Given that e-mail is supposed to be an efficient means of communication, it's a mistake to send overly wordy or detailed cover letters. They should be direct and to the point, clearly communicating what you're looking for and briefly summarizing your key skills and experience. A well-written e-mail cover letter will prompt a recruiter to take the time to read your resume. A lengthy, vague or non-specific letter will cause a recruiter to lose interest.

Your e-mail need only highlight your competencies and interests, says Andy Regrut, a former CFO who runs Friends of the General, an online recruiting and networking service in Columbus, Ohio, for former GE employees. "Don't go into detail, just give me enough information so that I can determine if it's worthwhile to review your resume," he says.

"And don't waste space by telling me you're going to follow up with a phone call," says Mr. Block. "In the first place, no one ever does; and secondly, a recruiter who's interested will call you."

Tailor your message to the employer's needs. A one-size-fits-all e-mail won't cut it with most recruiters and hiring managers. If you're responding to an advertised position, your cover letter will be most effective if it addresses the ad's specific requirements. Letters sent "cold" to an employer should relate the job seeker's experience relative to the company's perceived needs.

Carissa Franz, a Cincinnati trainer for a social service agency, took this route when she was looking for a job at a high-growth technology company. As a candidate for a master's degree in human-resources development, she found it nearly effortless to find a variety of ads for positions that matched her career goals as she cruised the job boards each evening in her pajamas. She kept a basic cover letter template saved on her computer and adapted it for each posting she targeted.

"I wrote a quick cover letter for each job I applied to," Ms. Franz says. "With my new degree, there were a number of areas I was qualified for, so it was important to relate exactly how my qualifications fit their requirements." She found a new job as an education consultant for Siebel Systems Inc., a San Mateo, Calif., company that makes customer-relationship software, by responding to a posting on Monster.com. The job description "rolled all my diverse qualifications into one job," she says. "I fit every one of its requirements to a T -- and I made sure to communicate that in my cover letter."

Put specifics in your subject line. If you want to annoy recruiters and hiring managers, send an e-mail with a vague subject line or none at all. The realities of online communications -- junk e-mail, computer viruses and high volumes of daily messages -- give busy professionals strong motives to ignore or delete messages with missing or ambiguous subject lines. "Tell me right up front who you are. Something like `high-tech product-marketing executive' will be really helpful to me," says Mr. Block.

If your e-mail is a follow-up to a conversation, refer to it in your subject line as well as in the body of your e-mail. A subject line like "follow-up -- resume of Karen Molloy" gives the recipient a compelling reason to open and read your e-mail.

Use your spell check and proofread your correspondence. Remember that people, not machines, will be reading your cover letter and resume. Lucinda Moore, a human-resources generalist for A-Carb LLC, Walton, Ky.-based manufacturer of brakes for the aerospace industry, says she often receives resumes and cover letters online that are sloppy and unprofessional-looking.

"Candidates should take the same pains to make sure they're communicating the right information, spell checking and proofreading as they would with a `real' resume," says Ms. Moore. "We print out the e-mails that we receive, and it's clear that people sometimes don't put a lot of thought into their cover letters. They're just not using the tool [e-mail] to their advantage."

Make sure that what you send by e-mail is something you'd want printed out and shown to a prospective employer. "Don't send me things you wouldn't want made public," she says.

Before you say thank you by e-mail, consider your audience. After interviews, Mr. Melnik sometimes sent thank-you letters or follow-up notes by e-mail, depending on the employer. "I tried to take my cues from the people I met with," says Mr. Melnik. "If they were technologically savvy and communicated extensively by e-mail, then I'd follow suit. But at some of the companies where I interviewed, traditional methods were still the preferred style."

He'd also send an e-mail when he felt it would give him a competitive edge over other candidates who might send a letter by "snail mail" that would arrive a few days later.

The medium you choose must be a good fit for the intended reader. In general, use e-mail when:

• Speed is of the essence. Unquestionably, e-mail is your best choice when you need to communicate immediately. Even a few hours or a few days can be too long in many fast-moving hiring environments.
• You need to demonstrate technology skills. If you're an older candidate, your e-mail might show that you're up to speed on technology. If you're in a high-tech profession, communicating via "snail mail" or fax could put you at a disadvantage.
• You're contacting a high-tech company. If everyone at the company communicates by e-mail, it makes sense to go with the flow, even if you're not a technical professional. You'll show you'll fit the company culture.
• You're communicating with recruiters. Without a doubt, e-mail is the preferred method of communication for executive recruiters. Using e-mail to send resumes and supporting documents makes their jobs easier.

When should you take the time to send correspondence through the regular mail?

• When sending thank-you letters. A well-formatted letter on high-quality bond paper makes a better impression than an e-mail note. You can write a longer letter, too, re-emphasizing relevant points from your interview and restating your qualifications as they relate to the needs discussed during your meeting.
• If you're a senior executive. Traditional mailed correspondence is still the recommended approach for senior-level executives, excepting those in high-tech fields. You can be more detailed and present a more professional image in paper correspondence.
• When the company and industry are low-tech. If e-mail isn't a well-accepted mode of communication for your prospective employer, you're better off using traditional methods.