Can't send email
Before doing anything else. When you try to send, do you get an error message of any kind? Write it down. You'll need that information.
Antivirus failing when scanning message
There's not much reason to scan emails for viruses when you're sending them. Of course you want to scan them coming in, but you wouldn't deliberately send a virus to someone, would you? Most antivirus programs can be set to scan incoming, but not outgoing, mail. This often helps.
There's a file attached which will take hours to send
Did you attach a file? How big is it, in megabytes? If you don't know, find out. More than 1 or 2 megabytes, it will take a long time to send and will possibly be refused by the other person's mailserver anyway. (Many ISP's mailservers refuse files bigger than about 6 MB.)
Outgoing mailserver settings are outdated
Is your computer using a different internet connection than it did before? If so, you probably should have changed to a different SMTP server at the same time. The usual rule is “If your broadband is through ISP X, use ISP X's SMTP server as your outgoing.” Here's a list of SMTP servers for some Australian ISPs.
SMTP authorisation problems
“Authorisation” just means “is the server going to accept your message”. There are several ways you can be authorised.
- If you're on ISP X's network, the server will have your IP address in its list, and will accept mail from you with no extra settings.
- Some servers allow you to login from any IP address. If you can't login, they won't accept your mail.
If you don't have one of these working for you, the outgoing server will say “Relay denied” or “Unauthorised”.
Failure notices
You send a message, but you get back a failure notice. It may look like a form letter, but do read it - it's the best troubleshooting information. If it doesn't mean anything to you, forward it to your friendly local IT person.