You might be interested in this article written by Jeremy Dent called "What are the differences between e-mail marketing (EMM) in B2B and B2C?":

I am often asked this question. Rather like the difference between consumer (FMCG) and business (B2B) marketing communications, there are five main factors that differentiates B2B and B2C email marketing (EMM): time; permission; creative; data and fascination!

1. Timeline
Most B2B acquisition e-mail campaigns have
lead generation as their primary aim. In B2C, that initial click
usually takes you to a landing page, then, within seconds, to a
shopping cart. A successful B2B e-mail marketer needs to capture
information from a landing page, but in a different way. A number of
additional steps (and often many months of additional time) are often
required to close a sale on a lead collected in this manner. The e-mail
message must be combined with an appropriate sequence of online and
offline communications: a phone call from a knowledgeable sales person;
a PDF document attached to a follow-up e-mail; extended information by
mail; perhaps a Web-based demonstration or conference call. For most
high-end products and services, a face-to-face meeting.

2. Permission
How much information should a visitor or
prospect give on a landing page before they can download a white paper?
Name, title, company name, address, phone and e-mail are standard.
Questions that are obviously qualifying (annual revenue, purchasing
authority, other DMU – decision-making unit – members) asked upfront
may result in a drop-off in the number of people who complete your
form. In B2B e-mail marketing, an implicit quid pro quo defines the
level of permission. The target audience offers valid information about
your company. The B2B e-mail marketer will, as a result, provide access
to a useful and informative guide or white paper. In B2C, it’s not just
an exchange of information. If the e-mail recipient enters name, phone,
and mailing address in response to a B2C promotion, it’s usually so you
can ship the item she purchased. In both scenarios, permission is
critical. In B2B, you need to specify that you will keep the
information private. You’re more likely to get registrants.

3. Creative treatment
Defining a compelling message for
your target audience and delivering it in the right tone of voice is
difficult. Which needs should you meet? An obvious gap in provision on
a company level? An implicit need of the individual receiving your
message? Both? In which order? The company level proposition means
identifying the business problem your prospect has: it could be lack of
sales or increasing costs. On a personal level, a motivator could be
the benefit of reading a white paper and being perceived as more
knowledgeable amongst their peers. There’s also the challenge of
crafting a subject line that captures one or both of these key message
points.

4. Data and targeting
The disparity between B2C and B2B
EMM continues in the number and quality of rental e-mail lists
available. The more targeted (and less IT-based) your audience, the
fewer B2B lists exist in which you can get detailed information about
the prospect and their company such as annual revenue, size of company,
and job function. Out-of-date email addresses are a bigger problem than
in B2C. Unless the marketing or sales director signs up with an e-mail
change of address service (ECOA), a business e-mail address is
untraceable once that person leaves company X for company Y. The legal
framework is less restrictive in B2B markets although I would always
advise a double opt-in method, a two-step campaign with new lists:
first, confirm interest and only then send the filtered list the main
offer. This will save you time and effort and also protect your brand
reputation. Of course, the ideal is to develop your own house lists
drawn from website visits, trade show attendees, seminars, direct mail
and sales contacts.

5. B2B: the more interesting option?
I believe that B2B
EMM is inherently more interesting than B2C. A typical high-value
purchase sales pipeline is drawn-out and complex. The DMU can be
extended and you may need different messages for purchasers, users,
influencers and gatekeepers. E-mail will be a part of a spectrum of
marketing communications tools: events; direct mail; advertising; PR;
website; literature in paper and electronic form; white papers;
telemarketing. But little beats EMM for immediacy, interactivity and
measurability.