以下是35条正式得体的英语生日祝福语，适用于商务邮件中向外国客户发送：

Wishing you a wonderful birthday and a year filled with success and happiness.

Please accept our warmest congratulations on your special day.

May your birthday be filled with joy and your year ahead with prosperity.

We wish you a memorable birthday and continued success in all your endeavors.

Sending you our best wishes for a happy birthday and a successful year.

On this special day, we extend our heartfelt congratulations and best wishes.

May your birthday bring you as much happiness as you bring to your business associates.

Wishing you good health, happiness, and success on your birthday and throughout the year.

It is a pleasure to extend our best wishes to you on your birthday.

May your special day be surrounded by joy and your future by endless opportunities.

We are delighted to wish you a very happy birthday and a prosperous year ahead.

Please allow us to offer our sincere congratulations on the occasion of your birthday.

May your birthday be the start of a year filled with professional achievements and personal joy.

With warm wishes for your birthday, we look forward to our continued partnership.

On your birthday, we send our best wishes for your personal and professional well-being.

Wishing you a day of celebration and a year of great accomplishments.

May your birthday be filled with the same level of excellence you bring to your work.

We sincerely wish you a joyful birthday and a successful year to come.

As you celebrate your special day, we wish you renewed energy and inspiration.

Sending our best wishes for a birthday that is as rewarding as your professional life.

May this birthday mark the beginning of your most successful year yet.

We are honored to wish you a happy birthday and express our appreciation for our collaboration.

Wishing you a birthday full of pleasant moments and a future full of bright opportunities.

On this important day, we extend our warmest thoughts and best wishes.

May your birthday bring you joy and your career continue to flourish.

With great respect, we wish you a wonderful birthday and a year of prosperity.

We take this opportunity to wish you a very happy birthday and continued success.

May your special day be as remarkable as your contributions to our partnership.

Wishing you a birthday filled with happiness and a year ahead filled with achievements.

Please accept our best wishes for a joyful birthday and a thriving future.

On your birthday, we wish you moments of joy and a path of continued success.

May your birthday be a refreshing start to a year of growth and accomplishment.

We extend our sincere wishes for a delightful birthday and a prosperous year.

Wishing you a celebration that matches your dedication and professionalism.

May your birthday be filled with warmth and your coming year with outstanding success.