@tanguatlay,
Quote:1) I would like to know whether I should use the present or past forms of the verbs in bold.
2) Are there any errors in the passage?
Many thanks in advance.
Customers will/would [1] send to [2] us the destination of the item that they want to be [3] posted via e-mail and we [will/would] return them a barcode which can/could [4] be printed out and affixed on the current stamp position on the letter.
Alternatively, we can/could also add value to our services by having customers send us the letters that they want posted by e-mailing us and we do the printing and sending of the mail for them. These two methods when implemented will/would both run on the basis of the introduction of the barcode stamps. The barcode stamps will/would allow customers to print out the stamps at their convenience without the hassle of purchasing stamps
My guess is that you are asking about the modal verbs, Ms Tan. They have no tense. In all the uses they all have future reference.
[1] You could use either will or would here. 'will' has a more definite sense while 'would' is more tentative [note that they both have future reference]. 'would' might be favored if this was a tentative plan
[2] The 'to' isn't necessary, though it is possible. It sounds more strident while without is more neutral/softer.
[3] 'to be' is also not necessary, though it too is possible.
Regarding the rest of the modal alternatives, the choice isn't one of tense. It's one of tentativeness/politeness/policy undecided/speaker intensity/and probably some other emotive feelings which are, after all, one of the main reasons for modal verbs.