It is common for MantisBT admins to report that they are having issues with users not receiving emails sent out by MantisBT. There are several reasons for this to happen:
- Emails landing in the recipient’s spam / junk folder
- Emails being rejected by the recipient’s email provider (these are lost).
- Emails being queued in MantisBT due to inability to connect or transfer messages to selected smtp server due to reaching daily quota limit (these are queued in MantisBT for future retries).
The rejection or placement into spam is typically driven by one of the following reasons:
- Using an IP with a bad reputation – common in case of shared hosting, hacked servers, IP recycling, etc. These IPs end up in black lists that are checked by SMTP servers before accepting emails from clients.
- Emails looking like they are spoofed – if emails are sent from a server that can’t be related back to the domain the emails are sent from.
- The contents of the email – this is typically not the issue in case of MantisBT emails.
The queuing of emails on the MantisBT due to inability to hand the emails over to the smtp provider is typically due to the following reasons:
- Using an IP with bad reputation – Most smtp servers will reject a connection if the IP is in some black list before even starting communication with the client.
- Hitting the daily quota – If an account sends too many emails, then servers would start treating it as a spammer or a user who is using this account for mass emailing which is typically not covered by the service agreement that is provided by services like gmail, hotmail, office 365, etc. This problem will look intermittent, since the limits are reset every day and hence emails will work for part of the day, then stop working and queue for the next day, etc.
In fact, we have hit a lot of these issues ourselves, and lately were hit with the quota case. Hence, we’ve decided to use a service that would take over the email deliverability for us, replace quota limits with pay as you go, manage IP reputation, provide reporting, and so on. This removes the headache out of this process and provide piece of mind that communication to users is reliable and predictable rather than having customers turned away because they registered and never got a confirmation email to activate their account. The cost of such service is based on the number of emails that are sent, hence, for most MantisBT instances, it should be low and well worth it.
We encourage you to try this out for free with a 1000 emails to get you started. Note that this setup providers you with an smtp server, account, and password that you can use with MantisBT, your forums, blogs, email clients, etc. In other words, you can use it for all your web apps and email marketing tools.