Problem with sending email from ipad

I am in Australia and, apart from an iCloud email address, have two email addresses, a bigpond.com address and a gmail.com address.

I have been unable to use my bigpond email to send mail when I have been at other people’s houses but, until recently I have not had a problem when at my own house. However, since about 6 or 8 weeks ago, I have been unable to send mail from my bigpond address at home as well.

I can receive mail addressed to my bigpond address anywhere but now find I can only send mail from my gmail and iCloud addresses. I can still send bigpond mail from my Windows computer so it is presumably not a problem with the email account itself.

I have not altered any of my email settings other than to add my wife’s email address to my iPad so don’t know why this problem has now occurred.

Can someone help me with this please?