当你需要催促一个外国领导回复邮件时，你可以使用以下英文表达：

1. Polite reminder: "Dear [Name], I hope this email finds you well. I just wanted to follow up on my previous email regarding [subject]. I understand you may be busy, but I would greatly appreciate it if you could take a moment to respond at your earliest convenience. Thank you for your attention to this matter."
2. Gentle nudge: "Hi [Name], I hope you're doing well. I wanted to check if you had a chance to review my previous email about [subject]. If you could kindly provide a response, I would be grateful. Thank you for your time."
3. Direct request: "Hello [Name], I hope you're having a good day. I'm reaching out to remind you about the email I sent on [date] regarding [subject]. It would be extremely helpful if you could provide a response as soon as possible. Thank you for your prompt attention."

请注意，在与外国领导交流时，尽量保持礼貌和尊重，并使用适当的商务用语。