LuxSci

Sending Outbound Email via IMAP?

Published: November 3rd, 2008

LuxSci has had various people ask if we support sending outbound email via "IMAP" and we have heard people say that they send a message via their "IMAP account".  What does this mean?  There is actually something behind this.

As many people know, IMAP is a protocol for checking email that resides on a server.  It is different from and more robust than the "POP" protocol that is also for checking email but which is typically used just for downloading messages from people’s INBOXes to their local computers.  With IMAP, you can have any number of folders and the email stays on the server for easy access from anywhere and so backups are taken care of for you.  That is a simplistic description, but the main point is that both POP and IMAP are for checking email only — there is no functionality in their specifications for sending email.

So, while some cases of people saying that they are sending their email outbound via IMAP can be chalked up to them just not knowing the difference between IMAP and SMTP, the other half of their email service that actually does the outbound email sending, some people really do send outbound email via IMAP.

How is this done?

Some email servers reserve a special IMAP email folder for outbound email messages … often called the "Outbox" or something similar.  When a user wants to send an email message "via IMAP" s/he composes it and saves it in this special folder (using IMAP).  Then, a special process on the email server looks for and notices a new message in that folder, sends it for the user, and deletes it from the folder.  Thus, as far as the user is concerned, s/he sent it via IMAP.

How is this useful?

This is useful if the user cannot use regular SMTP for some reason.  For instance, the user may be behind a firewall of some kind which prohibits him or her from sending email, but which allows use of IMAP.  With this mechanism, the user would then still be able to send outbound messages by copying them to the server over IMAP instead of SMTP.

Does LuxSci support sending email via IMAP?

No. This is a highly non-standard service offered by some companies.  However, LuxSci offers a wide array of alternate ports that can be used for sending outbound email messages via SMTP (regularly, using TLS, or using SSL) — including port 80.  These alternate ports resolve 99% of people’s problems with troublesome firewalls and allow users to "send email as usual".

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