Is it appropriate to use office email to apply for a transfer?
You may want to move on from your current job, but perhaps you are not aware that your best chance for a new job is to apply for an internal position. Many companies prefer to hire from within. Doing so not only means keeping an employee they like, it helps ensure any investment in training provided that individual stays at the organization and doesn't benefit a competitor.
What's the best way to apply to a job inside your company?
Your company likely posts positions on its website, but it may also list opportunities internally before advertising to outsiders. If you don't already know exactly how positions are posted, finding out should be your first priority. In this exploratory stage, you may not want to announce your intentions to everyone in the office, or to your boss, but a quick search on your company's website or a review of the employee handbook should provide the information you need about how to identify internal opportunities.
Don't forget to follow your own company on LinkedIn if it maintains a presence there, as it can be a great way to find out information about new job opportunities you may have missed.
Research your organization.
What kind of people does your company seem to like? You can learn a lot by talking to others who have worked in the organization a long time. What have their career paths been? Ask about their moves from one job to the next. Were they promoted? Did they take lateral moves to other departments? How supportive (or not) were their supervisors? Were there programs at the company they tapped into to help them plan and navigate their careers? Asking these and other questions can help you understand your organization's approach to internal transfers.
Prepare to explain your goals.
When you're seeking a promotion, it's easy to explain why you want to move from the job you have to the better opportunity. However, you may be considering a lateral move that doesn't come with more money or prestige. If that's the case, be ready to explain your motivations. Realistically, your goal may be to move away from a difficult boss, or perhaps you're hoping a new department won't expect you to work so many hours. Neither of these reasons are compelling from the institution's perspective, so be sure you plan a reasonable explanation that seems like a win-win. For example, you may explain that you want your skills to be more well rounded to enhance your ability to work with clients. Or, you have a very strong interest in marketing and believe your customer service background and skills provide a good foundation for being successful in the new department.
Talk to your supervisor.
Once you identify why you are motivated to look for a different position inside the company, and have seen at least one position that interests you, it's time to speak to your supervisor. Explain your goals and ask your boss to support your career plans. Keep the conversation very positive; do not indicate your desire to move reflects poorly on his or her leadership. Even if it does, it is not likely to help your case by sharing your feelings.
Apply for the job.
Yes, you can use your company email to apply for an internal position. Depending on the process, it may be the only thing that differentiates you from other applicants and will alert hiring managers that you're applying from within.
Even though you should have an advantage, don't rely on your internal candidacy to make the case for winning the job. Compose well-written and thought out application materials that describe why you are a good fit and how your accomplishments support your ability to do a great job in the proposed role. From the point of applying on, prepare and act as you would if you were seeking an external job. Take the process very seriously and plan ahead what you will say in an interview. Since you're an internal candidate, there's even more pressure on you to be able to describe how you can help the organization in the new role. Use every resource at your disposal to make a great case, and you could be moving offices before you know it.