Is it permissible to exchange emails or chat on Internet with his/her fiancée? Is it permissible to give wedding feast after one week of marriage? Will it be against the sunnah of Prophet (PBUH)?

If the parties are just engaged then it is not allowed for them to chat or exchange e-mails. Waleema should be within three days and scholars have said that if it were after three days it would be against the sunnah.
Original Source Link (from Way Back Machine archive)