SMTP Host Unreachable Error

Hi all,

My alerts were working fine till yesterday and no configs have been changed other than the device on which librenms is deployed was recently patched. After patching, I have started receiving error when trying to send email from librenms that SMTP host could not be found.

However, when trying to curl that snmp host from machine, I am able to reach it and getting proper response. Librenms logs are not showing anything relevant and I am not sure what can I check for this. Output of validate.php is provided below

===========================================

Component Version
LibreNMS 23.1.1 (2023-02-09T14:33:37-05:00)
DB Schema 2022_09_03_091314_update_ports_adsl_table_with_defaults (248)
PHP 8.1.15
Python 3.10.10
Database MariaDB 10.5.19-MariaDB-1:10.5.19+maria~ubu2004
RRDTool 1.7.2
SNMP 5.9.3
===========================================

[OK] Installed from the official Docker image; no Composer required
[OK] Database connection successful
[OK] Database Schema is current
[OK] SQL Server meets minimum requirements
[OK] lower_case_table_names is enabled
[OK] MySQL engine is optimal
[OK]
[OK] Database schema correct
[OK] MySQl and PHP time match
[OK] Active pollers found
[OK] Dispatcher Service is enabled
[OK] Locks are functional
[OK] No python wrapper pollers found
[OK] Redis is functional
[WARN] IPv6 is disabled on your server, you will not be able to add IPv6 devices.
[OK] rrd_dir is writable
[OK] rrdtool version ok
[WARN] Updates are managed through the official Docker image

Can someone please help with this?