Email limits on shared hosting: sending, message size and logins
PrintIn short: on TopHost shared hosting you can send up to 400 emails per hour, a single message may be up to 50 MB, and a mailbox accepts up to 50 logins per hour. Scripts on the hosting cannot connect to outside SMTP servers, some attachment types are refused, and mail from senders that do not exist is rejected. The details and the errors you may see are below.
The limits at a glance
| What | Limit | What happens above it |
|---|---|---|
| Outgoing messages | 400 per hour from the hosting account | further messages are discarded with an error |
| Message size, incoming and outgoing | 50 MB | the message is refused |
| Logins to one mailbox | 50 per hour | the mailbox may be blocked for a while |
| Scripts connecting to outside SMTP servers | ports 25, 465 and 587 closed | the connection fails |
| Dangerous attachment types | see the list below | the message cannot be sent or forwarded |
| Incoming mail from a sender that does not exist | not accepted | rejected with Sender verify failed |
400 messages per hour
Each recipient counts as one message, so one email sent to 50 people uses 50 of the 400. When the limit is reached, the server answers with:
Domain domain.tld has exceeded the max emails per hour allowed. Message discarded.
Messages above the limit are not queued for later: they are dropped, and you have to send them again. Sending is unblocked one hour after the mail account was last accessed, so repeated attempts during that hour only delay it.
Practical advice:
- Send newsletters in smaller groups spread over several hours, or use a dedicated mailing service.
- For regular large mailings a VPS with its own IP address is the right tool; see extra IP, reverse DNS and SMTP ports on a VPS.
- If you suddenly hit the limit without sending anything yourself, a mailbox password or a site script may have been taken over. Follow Spam notice or blacklisted IP at once.
Unsolicited bulk mail is forbidden by the TopHost Terms, and so is sending from addresses that do not exist. If spam or a server overload caused by mailing is detected, the shared hosting account can be suspended; under the Terms an account that sends spam can be blocked without prior notice.
50 MB per message
The limit covers the whole message, attachments included. Attachments are encoded for sending and grow by roughly a third, so a 50 MB message holds only about 37 MB of files. The recipient's server may accept even less. For large files, upload them to a cloud folder or to your site and send a link.
50 logins per hour per mailbox
Every time a program or phone checks for new mail it logs in once. A phone that checks every minute already exceeds the limit. To avoid having the mailbox blocked:
- set the check interval to 5 minutes or more on every device;
- remember that the phone, the office computer and the laptop all count towards the same 50;
- remove the mailbox from old devices you no longer use.
Failed logins with a wrong password are a separate matter: they can make the server firewall block your IP address. See why the firewall blocks an IP.
Attachment types that are refused
For security reasons a message with an attachment of one of these types cannot be sent or forwarded through the mail server:
- programs and installers:
.exe .msi .com .scr .pif .msp .mst .cpl - scripts:
.js .vbs .bat .cmd .jse .vbe .wsf .wsh .wsc .sct .hta .shs .bas - shortcuts and system settings:
.lnk .url .reg .inf .ins .isp .msc - help files and Access databases:
.chm .hlp .mdb .mde .adp .ade - certificates, saved messages and others:
.crt .eml .pcd
Two cases surprise people: .eml means you cannot forward a message as an attachment (forward it normally instead), and .js blocks plain JavaScript files sent by developers. Share such files through a download link.
Sending from your site: outside SMTP servers are blocked
Scripts running on the hosting (WordPress, contact forms, shops) cannot open connections to other mail servers on ports 25, 465 or 587. A plugin set up with the SMTP server of Gmail or another provider will therefore fail. Use one of these instead:
- the standard PHP mail function (sendmail) of the hosting;
- an SMTP plugin connected to a mailbox created on your own TopHost hosting, with the server and port shown in the mail client settings.
This rule applies only to scripts on the server. Outlook, a phone or any program on your computer connects to the TopHost mail server normally.
Sender verification for incoming mail
When a message arrives, the server checks that the sender's address really exists on the mail server of the sender's domain. If it does not, the message is rejected with the error Sender verify failed. This blocks a large share of spam. If a real partner of yours gets this error, their address or their domain's mail server is misconfigured, and they need to fix it on their side.
