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SMTP Relay Service FAQ

We provide an SMTP Relay Service for many of our customers. The price starts from £40 (+VAT if applicable) per year, for up to 5000 messages, or 750MB, per month.

How do I order the SMTP Relay Service?

To order the SMTP relay service, either email or telephone 01484 855801 where we can discuss the options.

Why is it not possible to order the SMTP Relay Service online?

We have had many problems with spammers ordering the SMTP Relay Service using stolen credit card details, so we have made the decision not to allow online purchases.

Is a trial available?

If you are an existing customer for one of our other products or services (eg VPOP3) then we can usually give you a 2 week trial with a small allowance for you to test that it works for you. Contact us at or 01484 855801.

What size subscriptions are available?

The standard sizes are:

  • 5000 msgs / 750 MB per month - £40 per yr
  • 7000 msgs / 1050 MB per month - £55 per yr
  • 10,000 msgs / 1.5GB per month - £70 per yr
  • 15,000 msgs / 2.25GB per month - £98 per yr
  • 20,000 msgs / 3GB per month - £125 per yr
  • 25,000 msgs / 3.75GB per month - £150 per yr
  • 30,000 msgs / 4.5GB per month - £175 per yr
  • 35,000 msgs / 5.25GB per month - £200 per yr
  • 40,000 msgs / 6GB per month - £225 per yr
  • 45,000 msgs / 6.75GB per month - £250 per yr
  • 50,000 msgs / 7.5GB per month - £275 per yr
  • 55,000 msgs / 8.25GB per month - £300 per yr
  • 60,000 msgs / 9GB per month - £325 per yr

Above that, it costs £25 per year for each extra 5000 messages/ 0.75GB per month

The above prices exclude VAT which must be added if applicable.

Note that the allowances are per month, and the price is per year.

There is also an 'unlimited' option for £30 (+ VAT) per month - note that this option is only available for existing customers because of the risk of it being used for sending spam.

How is the usage calculated?

Usually we calculate the usage on a rolling month basis, so messages are counted for the last month's worth of messages. e.g. at 11:53 am on 6th October, all messages after 11:53am on 6th September are counted.

If you wish, we can change this to run on a calendar month, starting at the beginning of the day of month that you subscribed to the service.

For most people, the rolling month basis is more appropriate. If you are always within your quota, then there will be no effective difference between the two systems. If you are send more messages than your quota, then the difference is that with the rolling month system, you will always be able to send at least some messages every day, as older messages become no longer counted, but with the calendar month system the last few days of the month you will not be able to send any messages at all once you have reached your quota, until the start of the next month.

Messages to multiple recipients are counted multiple times. So, if you send 1 message of 100kB to 1 person, that counts as 1 message, and 100kB size. If you send the same message to 15 people, that counts as 15 messages and 1500kB size. This is because, in most cases, the SMTP relay service has to send that message 15 times, once to each recipient, even though you may have just sent it once.

According to many sources, the average size of an Internet email message is around 50-80kB. A short text email will have a size of around 2kB. We have worked our message size quota out on the basis of an average size of 150kB per message.

A few people use their size allowance quicker than expected, because they have very large signatures with embedded images (e.g. we have seen cases where a short text message actually has a size of 250kB). We recommend linking to images rather than embedding them. This is more considerate to people who are charged for their Internet usage (eg on mobile devices) as well as reducing the mail usage.

When you send an attachment by email, it generally grows by around 33%, due to the attachment being encoded using 'base64' encoding by your email client. This is because Internet email was designed for pure text, so to send binary attachments, it needs to be changed into a 'text' form before sending.

What if we don't know what our usage will be?

Some people buy a bigger plan than needed, just in case, since it is not very expensive.

In other cases, you can purchase the plan you think you need, and then increase it later. The difference will be charged on a pro-rata basis.

Alternatively, you can use our direct-debit or variable pre-payment options (see the answer to the next question).

What if our usage varies wildly and/or is unpredictable?

If your usage varies wildly, it may be inefficient to buy a plan to allow your largest month's worth of email, every month. For instance if you usually send out 4000 messages per month, but send out 20,000 messages just before Christmas, it would be inefficient to pay for 20,000 messages every month.

In this case, there are three options:

  • If you know you will be sending out a large number of emails, contact us and we can increase your allowance for a month. Each month will be charged at 10% of the difference between the annual fees. e.g. if you have a 5000 message plan, and want to send out 25,000 messages in one month, that will cost (£150 - £40) * 10% = £11 (+VAT if applicable)
  • If the usage is totally unpredictable, then you may be better using our direct-debit option (within the UK only). In this case, you set up a direct debit with us, and each month we bill you based on the previous month's usage, at 10% of the annual cost for that usage size. You can set a maximum limit to prevent unexpected bills (e.g. if your system is compromised by spammers). This option is only available by direct debit because the bank fees for other methods of payment are too high given the low value of the monthly fees.
  • If you are outside the UK or do not like using direct debit, then you can use a similar option to the previous one, but in this case you pre-pay a certain amount (e.g. £200) and each month you use some of this credit based on the previous month's usage, at 10% of the annual cost for that usage size.

How do we set things up to use the service?

(These instructions do not apply to our “unlimited” service)

The mail server address is

Ideally you will connect to this server on port 587, using STARTTLS. Alternatively, you may connect without using STARTTLS, or connect on port 25 with or without STARTTLS, or connect on port 465 using SSL.

We will send you your username & password when you sign up for the account.

If you use SPF on your domain, add:

to your SPF record.

Are there any limitations on the service?

The service cannot be used for sending unsolicited commercial emails (spam), or anything illegal or immoral. If this is discovered your account may be suspended or cancelled without refund.

Can I monitor our usage?

If you log onto your account at, you can monitor your SMTP usage there.

(Not available on the “unlimited” service)

We use VPOP3 locally, can we prevent some users from using up all the allowance?

If you are using a recent version of VPOP3, you can set up send quotas for your users, so they can only send a certain number of messages themselves. To do this, edit the user, and go to the 'Quotas' tab.

faq/smtp_relay_service.txt · Last modified: 2021/06/29 09:35 by paul