sender address rejected by service iPhone

I have many times sent images I take on my iphone to myself at home to import into iphoto with no problem. Today I try to do this and I get a message A copy has been placed in your outbox. The sender address (mine) was rejected by the server. I phoned my server shaw.ca and they say it is a problem with the phone. Why would this work a few days ago and not now. Any comments would be appreciated.
PS new phone at Christmas
Thanks.
Macbook Pro 4 GB Ram SL Mac OS X (10.5.7) Imac 24" 3.o6 GH 4 GB ram, iphone 4 32GB