In writing only...
Good afternoon 午安 (Avoid using this phrase as much as possible. This is not a natural greeting in Cantonese culture.)
To whom it may concern 敬啓者
Please let me know 煩請告知
My best e-mail address is XXX 聯絡電郵為 XXX (Reverse translation: My contact e-mail is XXX.)
Best Regards 謹上
If you want to properly communicate in writing, you'll have no choice but to learn Standard Written Chinese, that is, you'll have to learn 中文 again.
Good afternoon 午安 (Avoid using this phrase as much as possible. This is not a natural greeting in Cantonese culture.)
To whom it may concern 敬啓者
Please let me know 煩請告知
My best e-mail address is XXX 聯絡電郵為 XXX (Reverse translation: My contact e-mail is XXX.)
Best Regards 謹上
If you want to properly communicate in writing, you'll have no choice but to learn Standard Written Chinese, that is, you'll have to learn 中文 again.