Hmmm maybe this software has been deprecated for this decade for us as an email client. But i believe there are some people still using it :D. At this little note, i just wanna share about my experience why outlook express can’t sent email. Let check this one out.
1. Your SMTP / IMAP configurtion is wrong
Please check your SMTP / IMAP configuration based on your provider. Maybe there something miss.
2. Check your Sent Item.dbx filesize
This is cause your email can not sent well. As we know dbx file, only 2GB, so if your Sent Item.dbx has reached this size just recreate your Sent Item
3. Check your anti virus
If your antivirus has feature scan email. Just disabel it for a moment.
4. Check your connection
Chek your connection is good or not. If your connection is good but you can still sent email. Try to repair it. May be software XP TCP IP Repair can be a choosen one.
Have analyze it. It Just Share if this note is give advantage just use it but if there as something wrong just PM me.