Q: MCMailErrorDomain error 1045

Back again - within an hour it wouldn't send mail again - this time because 'no outgoing server was set' ... huh?

When I went into accounts.. for some of my email accounts the outgoing server had been set to 'none'.

These are accounts where (for specific reasons) I don't  want them bringing in the incoming mail, but I only use them to send outgoing mail from a specific address like admin@mydomain.com

I presume the feature to "Automatically detect and maintain account settings" had re-set all these accounts, and because there was no incoming mail server detected it had concluded there is to be no outgoing mail server?

So I reset all my mail accounts to the correct outgoing mail server and UNCHECKED the box again to "Automatically detect and maintain account settings"

I tested it and it is still working (for now)

So I'm wondering if this is a new feature?

Never had this problem before until I did the Yosemite software update 2 days ago.

We'll see how long it keeps working this time & will keep you posted.

After using Apples devices since 1992 (Mac IIfx) I am at my wits end.  My email doesn't work any more despite all the help these pages provide, and all the advice being given is to no avail.  Despite having an apple ID for years I have just been denied access and had to initiate a completely new ID and password across the board.  All this eems to be in the general dunning down of Apple's previously excellent simple interface.  Want evidence?  What ever happened to the excellent Aperture program?

The problem is that Apple wants to define your Mail settings without knowing what your provider needs.  The conflicts that are set up appear to be insurmountable as my SMTP Out is now permanently offline.  How convenient, I can't even email Tim Cook without first setting up a different email account with me.com.

I have spent hours trying to solve this problem and have now put it in the hands of Tim Cook.  Life is too short to have to worry about SMTP settings that Apple keeps altering even when the box is supposed to be unchecked.

<Edited by Host>

Yeah. I am a long time mac user, since 1985, and I am unable to send email I have spent 24 hours on this of work. I have tried EVERYTHING described here, and nothing works. Nobody seems to know what a 1045 error is. And I am not getting ANY headway, at all. 

I am sorry I updated by OS, because it was only AFTER I did so that I had these problems.

Seriously, Apple, this is an issue. Why is it an issue when so many peope have the SAME problem?

I am ready to toss this computer in the river.

I've had the outgoing smtp problem that several have mentioned.  Did what you suggested, and logged in as another user on my same macbook pro.  Worked perfect! (all same settings, etc)

What is it in the User folder (as you mention in your post) that I need to look for and get corrected?  Please!  Thanks!

I agree with you, ruth_uk, that this problem started with the latest update (version 10.10.4 on a late 2011 MacBook Pro). I started having this problem when I made this update and even went to a store that sells Apple products (we don't have "Apple Stores" in México, just some that look like them, but can't use their name) to ask for help, 'cause I couldn't solve it for myself, and, after about half an hour, the guy that was helping me tried the "installing the account in another user" trick and, when we changed the outgoing server settings under my user account, it started working again (by that, I mean that I could send an e-mail using my internet provider outgoing server). The settings were the same we were using before, but then they started working fine.

To be more explicit, I'll send here a list of some problems I had (and I am having again) specifically with this account (gmail is working fine for now, but I just set up the account in Mail yesterday):

- the outgoing server port changed as it pleased (not anymore)

- on the list of outgoing mail server, my internet provider server is put automatically to Offline

- I also receive that error 1045 message

- and i can't send mails, just receive them.

I've done everything suggested here and nothing is working for me. That's why I set up my gmail account and now I'm starting to notify everyone that they must use my gmail account, not my internet provider's anymore. Or, when I need to send something, I choose the gmail outgoing server. But I really would like to have a solution to this problem, even if it has to come within another update.

Anyway, if anyone has another suggestion, I'm all ears!!! Thanks!

Bizarrely, this is exactly what happened to me! After years of using the same SMTP protocols it started giving me the same error 3 days ago! Tried EVERYTHING as you did and viola! Changed the "automatically detect settings" on AGAIN and it just worked!!!

I just ran into this problem updating the Apple mail client with an older email hosting account (that does not support securely sending email via SSL encrypted SMTP connection), and didn't find any helpful information anywhere. I eventually determined that installing the Apple Mail Client will set accounts to a default expecting an SSL encrypted SMTP connection, and if it is not supported by your server, it will fail and throw the error code "MCMailErrorDomain error 1045," which I easily resolved in the following way:

Mail -> Preferences -> Accounts -> (select account from list) -> Account Information -> Outgoing Mail Server (SMTP) -> Edit SMTP Server List -> (select server from list) -> Account Information -> Allow insecure authentication (box checked)

Problem solved.  A better (more secure) solution would be change or update your email hosting solution to one that supports SSL SMTP on the server side. It is possible that your email service provider already offers this and all you have to do is update your settings by selecting "Use SSL" and change the port number (both in the same dialog box as above) according to the instructions from your ISP provides (usually port 465 for SSL or port 587 for StartTLS).

Thanks Ruth. This worked.  The other thing that popped up was malphish which Sophos then quarantined.

Don't know if it was related.

Aleluya! El Capitan Update Mail.app Problem

Thanks for the tip.  I updated a 2008 MacBook Pro from Snow Leopard to El Capitan.  I expected a few issues when upgrading (but hoping they wouldn't be as bad as Windows upgrades).  Some applications were no longer functional on Snow Leopard, so I felt compelled to finally upgrade.  Some things are different, but I will get used to it.  The installation went smoothly, about 35 minutes to download and a bit over an hour to install.  On verifying functionality my long established e-mail account at Frontier wouldn't send or receive messages.  After 2 hours of googling the problem and trying a bunch of changes on account settings I finally checked the boxes on 'Allow insecure authentication' on both the outgoing SMTP server and the incoming POP3 server.  For now things seem to work.  Next issue is that I can print to one printer but not a second one, although there is no error indication...the print job just disappears into never-never land. 

Thanks. This did the trick..finally..after trying all that is mentioned before this.

I recently updated my Father's Mac mini from mavericks to El Capitan (I'm not sure why he never updated).  He was receiving error 1045 right after the update.  I ticked the box "Allow insecure authentication" and then his mail started sending.  If this was a problem starting in 2014, can I assume that a real fix was never put out?  It's not a big deal, since  my dad's mail is working now, but I'm just wondering.