Comment 10 for bug 1538058

After some research it's been decided to leave mail sending as SMTP only, at least for now: interfacing with mail/mailx is much more complicated in Python than it is in PHP, for little visible gain.

Both changesets are ready for merging and adding to custom-scripts:

https://review.fuel-infra.org/#/c/16196/
https://review.fuel-infra.org/#/c/16416/

Required credentials for the script:

1. SMTP account to send email from. Local SMTP is acceptable.
2. Script configuration file: /etc/custom_scripts/escalate-reviews/escalate-reviews.conf (use escalate-reviews.conf.example from Gerrit changeset as the base).
3. Configuration file needs SMTP credentials (host, login, password, FROM address). If a certificate and/or private key are required for SMTP server, their paths are specified in configuration file.
4. Private key for Gerrit access to review.openstack.org. Script expects to find it in /etc/custom_scripts/escalate-reviews/review.openstack.org but other path can be specified in configuration file.