Maximum e-mail sends for 1 day on mail cow

Batool

Hello everyone,
Hope you’re having a great day!

I have a quick question, what is the maximum number of emails that a Mailcow server can reliably send in a single day? Are there any built-in limitations, or is it mainly dependent on server resources and IP reputation?

Thanks

ETNyx

Hello,

in theory there is no soft limit, so what your system is able to send it’s processed.

But there are other factors, big players like Gmail and so, will measure how many mails you send, how many are spam a they will limit how many mail you are delivered. To overcome this you need to do “warm up” your server. That’s basically means start small and gradually send more and send good mail (no spam) and monitor,..

Simplified overview about your sending history (volume, reputation) can be find https://www.gmail.com/postmaster/ https://www.talosintelligence.com https://sendersupport.olc.protection.outlook.com/snds/index (hmm ms seams to be phased out ??)

Batool

Thanks for your quick response
I currently have around 1,179 emails stuck in the mail queue, which is causing delays. This is because I have more than 10 service accounts that send hundreds of emails per day and thousands per week.

Is there anything I can do to reduce this delay or optimize the delivery process ?

Appreciate any suggestions!

esackbauer

Batool Is there anything I can do to reduce this delay or optimize the delivery process ?

Use a proper smtp mail relay service for mass mailing, like mailgun or smtp2go.

ETNyx

Well question is in what state your mails are in queue? Not sure if this information is in MC UI (my is empty), can you make a screenshot? Other than that you can use postqueue command what you want is -p and check if mail in queue is active or defered, if so you should see reason in postfix log.

Batool

Alot of thanks for your answer

This is the error for each mails in queue from command: postquesue -p

delivery temporarily suspended: host cloud-out-c.spamtitan.com[52.5.202.67] refused to talk to me: 421 4.7.0 cloud-out-c.spamtitan.com Error: too many connections from <mailcow server IP>

ETNyx

Yes, pretty self explanatory, now I do not have enough time to make a research, but depended on how this server make it’s accounting you may be able to tweak your postfix to send bulk of message in one connection and delay next [docs](https://www.postfix.org/postconf.5.html) look for destination_concurrency_limit, destination_rate_delay those should help you whit timing of your queue. Please make your research about this,…

Batool

Thanks a lot for your time, I will research