Hi Maarten,
You can try a solution that worked for me in a slightly different context unless you have other constraints (my provider did not rely on using "from" address as a username, which VocBench assumes, but rather used a separate username and API token).
1. Host a separate SMTP relay. It is pretty lightweight and does not take much memory or CPU - here's a snippet of what my Docker compose file looked like assuming you can use TLS with your provider as per your last messages (obviously you need to take care it is not reachable by hosts other than your VocBench host, etc.):
smtp:
image: namshi/smtp:latest
ports:
- "25:25"
environment:
- SMARTHOST_ADDRESS=
smtp.sendgrid.net - SMARTHOST_PORT=587
- SMARTHOST_USER=apikey
- SMARTHOST_PASSWORD=XXXXX
- SMARTHOST_ALIASES=*.
sendgrid.net2. Configure VocBench with plain unencrypted SMTP on port 25 (in this case inside Docker compose or in Kubernetes with config as per #1):
Mail SMTP host: smtp
Mail SMTP port: 25
Cryptographic protocol: None
Hope this helps.
Eugene.