Welcome to Deanspot.org...

I've used Mozilla Thunderbird as my email client for years. Overall, I love it. Spam filtering is top-notch, the threaded view is great for reading mailing-list traffic, it's an RSS reader, and the huge range of free extensions allow me to add all sorts of functionality that isn't in the base application.

But, I've always had one annoyance which I just lived with, until today. I finally figured out how to use multiple SMTP servers in Thunderbird. TBird has a very easy-to-find configuration pane which allows you to enter multiple SMTP servers, and set one of them as the Default. Cool. But, no matter which one you set as the Default, clicking the Send button to send an email would always try to connect me to the very first SMTP server I'd entered, regardless of which was the Default.

This was an issue because my ISP only allows me to connect to their SMTP server when I'm on their network (at home). When I'm travelling, I can't send mail out using their server. I have an account on another server I can use, but for the reason I just mentioned, I have never been able to easily switch from one to the other in Thunderbird. I would end up deleting my home config when I was travelling, and have to re-add my home config when I got home. Stupid.

What I finally figured out today is this : It's a Thunderbird configuration issue which I think maybe should be reported as a bug. There are 2 places in the Account Settings which are relevant. Thanks to this Mozillazine article on multiple SMTP servers in Thunderbird.

1. The 'Outgoing Server (SMTP)' pane in 'Account Settings'. This is the obvious one. You can enter multiple servers, and set one as 'Default'. But normally, no matter what you do, 'Send' won't respect your choice.
2. In 'Account Settings', the main pane of each account has it's own 'Outgoing Server (SMTP)' drop-down box. By default, this is set explicitly to whichever server is Default when you create the account, and that's the one which will be used when you send mail from this account. You can change this from a specific server to the value 'Use Default Server', and then the 'Default' setting magically starts doing what I'd been expecting it to do all along.

Armed with this revelation, I installed the nifty SmtpSwitch extension. This turns the 'Send' button into a drop-down box where I can pick which SMTP server I want to use. But it only works if your email account has the 'Use Default Server' option selected for 'Outgoing Server (SMTP)' in 'Account Settings'.

I think I finally understand how this works, technically. But it's not at all what I expected. To Thunderbird, the 'Default' SMTP server is the that's set as the outgoing server for any new account. But this is done only at account-creation time. I'd always expected a check of the 'Default' setting to be done at email-sending time. I can see that if this was the way it was, you'd never be able to pin 1 email account to a specific SMTP server, but I've never had a desire to do this, so it's a big who-cares in my mind.

I guess if you always want mail from 1 account to use the same SMTP server, it's the correct way to do things. But for me, I don't base my choice of SMTP server on 'which account I'm sending from'. I base it on 'where am I at the time', as I mentioned above.

I noticed that SmtpSwitch received several negative reviews because people said 'it doesn't work, it always uses the same server'. I'm willing to be these folks ran into the same issue I'm describing here. Drag. It's not the extension author's fault, it's Thunderbird's opaque understanding of what 'Default' means.