Error to respond any mail

[rubio.marcos]

hi good day.

I hope you can help me, i´ve a problem when push respond any mail, when i try to send my email, and select send, a emergent window appear with the message, "the server or network is slow to respond" and after appear the message "An error ocurred in the network service". But i if delete the word RE: on subject, dont appear any emergent window, thanks for your help