Before transferring a large sum, double-check the beneficiary's name and account number (or IBAN) exactly, and verify the bank, currency, and purpose of the transfer.
Steps
If the beneficiary is new or you received the information via email, confirm it with them through an independent communication channel to prevent fraudulent changes to the transfer details.
Be aware of the channel's limits, fees, and required bank documentation beforehand, and keep your receipt and transaction number.
If the amount is substantial or the information is unfamiliar to you, perform a small verification first when practical, rather than risking a full transfer based on unverified information.
The figures, fees and limits in this answer vary by bank and change over time — confirm them with your bank or the official source before acting.