I have had my iphone for at least 2 years and in that time I have used it to send and receive emails through my Virgin media email account. I have not once had a problem. Up until today. I can receive emails but not send them. I have checked all the settings and they are precisely as they should be and exactly as they are on the other devices I use which I have no problems with. The settings have not been changed in any way recently. I have tried changing my password since to hopefully solve the problem, but the situation remains the same.
Please note I am not a software engineer so please explain step by step what to do and do not leave out steps.