It is most frustrating to send a message and not know if it has reached its target. E-mail is a relatively new media, and senders need to be reassured that their missive has not ended up in the bit bucket. If there is going to be a delay in answering, you should at least notify the sender that the message has arrived. A fast answer might consist only of the words OK or thanks. If it takes more than 10 seconds for that whole procedure, then you are doing something the hard way.
Newcomers have a tendency to use multiple e-mail addresses when they use more than one provider.
This is confusing. It is best to have only a single address which will save you time in looking for your mail. It will also avoid confusion for the senders who generally will want the mail to reach you as fast as possible. On the other hand, it makes sense to use different addresses for various uses, such as work and home. If your Internet provider is not reliable, then you may want to have a backup address.