From MozillaZine Knowledge Base
- This article was written for Thunderbird but also applies to Mozilla Suite / SeaMonkey (though some menu sequences may differ).
Thunderbird doesn't formally support POP before SMTP, a way to verify that a user is allowed to use a SMTP server by having the e-mail client log into the POP server shortly before sending the message. Its sometimes called LB4S (Login Before Send) or POP AUTH. You can check for new mail and then send a message but you may have problems doing that in the amount of time your email provider allows. Some workarounds:
- Use the "Get before Send" extension.
- Install the offline extension (bundled in the Thunderbird setup program) and use the "Send Later" button to queue the message to the Unsent Messages folder. If you check for new mail for the POP account and then use "File -> Send Unsent Messages" to send all of the queued messages it should make it easier to send the message(s) within the grace period.
- Change "check for new messages every X minutes" in Tools -> Account Settings -> Server Settings to a value that causes it to login within the grace period.
- Install a local SMTP server. This isn't as hard as it sounds. In fact some add-ons to add webmail support such as Ypops! include thier own SMTP server.
- Make your connection through a "POP before SMTP" proxy.