Postfix receive email after bad configuration

I had a bad configuration on my postfix server so I didn't receive email.

After my correction (delay 24h) I receive email but not all one shot, maybe one email by 15-30min. Is there a command for mail server sender to "ask" to resend email or I need to wait?

I'm afraid to lost email.

Thanks

My answer to your question, that you are

I'm afraid that emails will be lost

is as below:

If the Sending email server is not able to pass you the email through SMTP Port(TCP 25) because of any issue, it will queue and keep the emails on the email server's side(Sender Side). But for how long? The answer to this question: Depends on the email server administrator. Someone may keep it for 1 day, someone may keep it for 3-6 hours or so.

My Suggestion for critical scenarios is to have multiple emails servers setup as RelayServer and point your MX to those.Thus if something goes wrong on the main mail server(mail server with the accounts on), you have multiple mail server behind, which receives and queues the emails, and as soon as your issue is fixed, you just need your relay servers requeued to send the queued emails to your main email server.

No, in general there is no such command. Answer first, who to ask about mails? How are you going to know who attempted to deliver mail to you?

If the misconfiguration on your server gave them 4xx response code, or no response, e.g. no connection, don't be afraid. Usually servers queue and retry emails for a week or so before giving up.

Also notice retries usually are done in "increasing delay" fashion, so first retry is 1 minute after the initial attempt, next retry is 5 minutes later, then 10 minutes, maybe hour and so on, up to a whole day. So if your server has been inoperable for a whole day, chances are you have to wait another whole day until everybody retries their delivery.

The suggestion of having a "backup MX" is nice, but requires additional configuration. You may set up an additional "satellite" relay host who'll queue all the mail destined to you and then you will be able to ask it to deliver now, when you are online; that thing is called ETRN service. Now you know who to ask - your own backup MX server, who collected all the mail when your primary server was offline. But notice you can't just use this feature with any other email server, because it won't work. The service usually is not available for domains not specifically configured, and it's unlikely your domain was configured for ETRN service on the servers from which you expect your mail.