Problem sending from Gmail

Do you get any kind of error messages when trying to send?

If it's an authentication problem then you could try the experimental XOAUTH2 support in MailMate. As far as I know it's not necessary in general, but if it works for you then you probably won't care about that :-) See more here.

Just to emphasize: XOAUTH2 should also mean that you don't need to allow what Google likes to call “less secure apps” (I don't really appreciate that Google insinuates that anything not following their lead is “less secure”. It's their design that 1 password provides access to all their services.)

I just ran into the same problem. I got the following message from Google:

Sign-in attempt prevented

Hi Donna,
Someone just tried to sign in to your Google Account xxx@gmail.com from an app that doesn't meet modern security standards.

Details:
Tuesday, September 8, 2015 7:09 PM (Pacific Daylight Time)
Corvallis, OR, USA

We strongly recommend that you use a secure app, like Gmail, to access your account. All apps made by Google meet these security standards. Using a less secure app, on the other hand, could leave your account vulnerable. Learn more. https://support.google.com/accounts/answer/6010255

Google stopped this sign-in attempt, but you should review your recently used devices:

REVIEW YOUR DEVICES NOW

I reviewed my devices and indicated that the scary device was in fact mine, but the error persisted. Then I allowed access to "less secure apps" and it works now. This is a throwaway account that I use only for Craigslist postings, so I'm okay with less security.

The weird thing is that I have another Gmail account that is using a custom domain name (via Google apps) and it works just fine in MailMate.

Donna

@Donna: Google is really arrogant about this, but at least they are honest about their motive: Everyone should use the Gmail web interface.

Thanks for letting me know about this warning. The only thing I can do is to make XOAUTH2 the default behavior. The user experience in a Desktop email client is not very good though (switching to a browser and requiring copy/paste) and it's bound to confuse a lot of users...