Copyright © 1999–2019 FastMail Pty Ltd
We apply fair use limits across our service to prevent abuse or runaway activities from accidentally using up too many resources. In general we will notify you when you have reached a limit by emailing you. Details on our most common limits are below.
Limits on storage space
There are two main storage limits for every user: one for mail, calendars and contacts, the other for file storage. The limit per user depends on your account plan, as detailed below.
You can see how much of each quota you are using at the bottom of the sidebar (below your list of folders) in the Mail and Files respectively.
We will email you if you get close to your storage quota limit. You should either delete some of your existing data to make room (make sure you empty your trash to recover the space if you are deleting mail), or add email storage quota or upgrade your account.
When mail storage quota limit is reached
If you go over your Mail storage quota, further mail sent to your account will be temporarily rejected. The server that sent the message is sent a
4xx code which instructs it to try again later. This means if you get your account back under the storage limit quickly (either by upgrading your plan or deleting some existing data), no messages will be lost. If your account remains over storage quota for a week, we will change to returning
5xx permanent error messages. This means all messages sent to your account at this point will bounce, and be returned to the sender as undeliverable.
These restrictions are lifted as soon as your account goes back under quota.
Quota limits for other services
The following limits are per user, and are the same for all plans:
|№ Fetch accounts||50|
The following limits apply to the account as a whole, depending on the plan:
|№ aliases||600, plus 15 for every user in the account|
|№ domains||None||100, plus 1 for every user in the account|
Limits on sending/receiving email
Limits on per-message attachments and message size
You may send any kind of attachment, as long as the resulting email is under 70 MB in size (due to encoding issues this usually means an attachment of 50 MB). Attachments with double file extensions (e.g.
filename.doc.exe) are not allowed, as they are commonly used for virus transmission.
The same maximum size limit of 70 MB (due to encoding issues this usually means an attachment of 50 MB) applies to received email as well.
Limits on total number and size of messages sent/received
To protect our service against abuse, we limit the number and total size of emails that can be sent and received. These limits are very high and 99.9% of our users never get anywhere close to hitting them. If you find yourself regularly getting close, you should upgrade your account. If you are already at the top plan, contact our support team to discuss your needs.
The following daily limits apply per user, depending on the plan:
|Number of messages received||4,000||8,000||80,000|
|Total size of messages received||1 GB||2 GB||4 GB|
In addition to the daily limits, there is a per-minute limit of 100 messages/100 MB. This limit is the same for all account levels and is to stop large email floods overloading an account.
We also have limits for the number of received messages from a single sender, to stop an automated system accidentally flooding your account and stopping other email from being received. No mail being received from a single sender can exceed half your per-day or per-minute allowance.
The following daily limits apply per user, depending on the plan:
|All Trial users||Basic||Standard||Professional|
|Number of messages sent||120||4,000||8,000||16,000|
|Total size of messages sent||250 MB||1 GB||2 GB||4 GB|
Please note, to prevent abuse, all trial accounts are limited to sending a maximum of 120 messages per day. The sending limit is lifted to the full account quota as soon as the account is paid for. Also, note that when you send an email to multiple recipients, your quota is updated once for each recipient.
In addition to the daily limits, there is an hourly limit for each of these quotas which is half the daily limit, and a 10-minute limit, which is half the hourly limit.
Bandwidth limits: files and websites
To protect our service against abuse, there are per-hour and per-day limits. They apply to how much is sent from your website (webpages and associated content), as well as what is uploaded and downloaded from your file storage. The bandwidth limits are dependent on your plan.
The following daily limits apply:
|All Trial accounts||Basic||Standard||Professional|
|Number of files/webpages/images uploaded or downloaded||1,600||40,000||80,000||160,000|
|Total size of files/webpages/images uploaded or downloaded||20 MB||1 GB||2 GB||200 GB|
In addition to the daily limits, there is an hourly limit which is half the daily limit, and a 10-minute limit, which is half the hourly limit.
Each individual file can't be larger than 50Mb.
What happens when limits are reached
When a limit is reached, further attempts to send/receive emails or upload/download files or service webpage requests (depending on the limit breached) will be blocked. For emails the block will display a temporary
4xx type response. This does not result in email being bounced, only delayed: the sending server should try again later.
The rate tracking counter is activated on the first event received of its type (email or file), and reset 1 minute/10 minutes/1 hour/24 hours after the first event received.
We only update the rate tracking information after the request has completed. This means you can upload a file as large as your file quota to your file storage area regardless of the 10 mintute bandwidth limit. It's possible that the upload will take some time to complete at the end of the upload. The entire file has to be transferred to multiple servers to ensure it's safely stored, and we won't return an OK response to the upload until that's completed, which could be many minutes with a gigabyte sized file.
Here's an example for a user uploading and downloading files with a 1000 MB hourly file transfer quota:
- 10 MB uploaded. Counter starts at 10:15. Counter = 10 MB.
- 20 MB uploaded. Counter = 30 MB.
- 500 MB downloaded. Counter = 530 MB.
- 500 MB uploaded. Counter = 1030M. You are allowed the download/upload event that sends you over the hourly limit, but none after that until the counter resets.
- 10 MB download attempt fails. Counter = 1030 MB, over the limit of 1000 MB.
- Counter resets.
- 200 MB downloaded. Counter starts at 11:30. Counter = 200 MB.
Why is the size of a message larger than the attachment?
Email is an old standard from many, many years ago that originally started as purely text data. Over time, as people wanted to send attachments, they updated the standard to include them, but also tried to keep it backward compatible so older email systems wouldn't "break" the messages.
To do this, any attachment added to an email is usually encoded into a form called "base64". In this system, each group of 3 binary bytes is encoded into 4 ASCII characters. This means a couple of things:
- All characters in emails are always ASCII so existing systems are not confused or broken
- Any binary attachments are expanded by 1/
3 (33% bigger, so 30k becomes 40k, etc.)
Our IMAP server stores emails in their original form, so any emails with attachments will be about a third bigger than the actual size of the attachments when you download them. The sizes reported on the mailbox screen, and the totals reported on the resource usage screen are of the original email as it is stored in our server.
Limit on logins
There is a per-user limit of 500 (successful) logins per 10 minutes across all services, including IMAP logins, POP logins, SMTP logins, FTP logins, etc. Most users will never get near this limit: it's there to protect against poorly implemented or designed software, or incorrect settings.