**Solved** Gmail SMTP error - TLS Negotiation failed, the certificate doesn't match the host

Gmail has changed how they check certificates and email sent via SMTP bounce back with the following error:

“You’re sending this from a different address or alias using the ‘Send mail as’ feature. The settings for your ‘Send mail as’ account are misconfigured or out of date. Check those settings and try resending.
The response was:
TLS Negotiation failed, the certificate doesn’t match the host.”

I set up SMPT Server in Gmail as mail.mydomain.com on port 587.
That is no longer working because it appears that mail.mydomain.com does not match the email host email@mydomain.com

More info about it are here


anyone else experiencing the same issue
CentOS Linux 7.7.1908
Virtualmin 6.08

I requested new certificate from Virtualmin UI and manually included mail.mydomain.com. After a short while emails started to work again.

That’s not what the error says.

The error says the certificate does not match the domain you’ve told GMail to connect on. So, make sure the certificate Postfix is using is one that includes mail.mydomain.com or configure GMail to connect to a name that is included in the certificate.

Hi Joe,

thanks for your reply,
The certificate is for mydomain.com. However, gmail will not connect to mydomain.com for the emails. The error is: Server is too slow to respond.

I’ll try and see how to have a valid certificate for mail.mydomain.com

it looks like mail.mydomain.com is included in the cert by default and in fact it was working until yesterday.

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